Table 17-2 lists the LOB functions that use the LOB locator that are described in this section. Use functions that end in "2" for all new applications.
Note:
There is another way of accessing LOBs -- using the data interface for LOBs. You can bind or define character data for aCLOB column or RAW data for a BLOB column, as described in these locations:
"Binding LOB Data" for usage and examples for both INSERT and UPDATE statements
"Defining LOB Data" for usage and examples of SELECT statements
| Function | Purpose |
|---|---|
|
Start user duration for temporary LOB |
|
|
End user duration for temporary LOB |
|
|
Append one LOB to another |
|
|
Read LOB data for multiple locators |
|
|
Write LOB data for multiple locators |
|
|
Assign one LOB locator to another |
|
|
Get character set form from LOB locator |
|
|
Get character set ID from LOB locator |
|
|
Close a previously opened LOB |
|
|
Copy all or part of one LOB to another. This function must be used for LOBs of size greater than 4 GB. |
|
|
Create a temporary LOB |
|
|
Turn LOB buffering off |
|
|
Turn LOB buffering on |
|
|
Erase a portion of a LOB. This function must be used for LOBs of size greater than 4 GB. |
|
|
Close a previously opened |
|
|
Close all previously opened files |
|
|
Check if a file exists on the server |
|
|
Get directory object and file name from the LOB locator |
|
|
Check if file on server is open using this locator |
|
|
Open a |
|
|
Set directory object and file name in the LOB locator |
|
|
Flush the LOB buffer |
|
|
Free a temporary LOB |
|
|
Get the chunk size of a LOB |
|
|
Retrieve the user-specified content type string (a file format identifier) for a SecureFile |
|
|
Get length of a LOB. This function must be used for LOBs of size greater than 4 GB. |
|
|
Get option settings of a SecureFile |
|
|
Get the maximum length of an internal LOB (BLOB, CLOB, or NCLOB) in bytes |
|
|
Compare two LOB locators for Equality |
|
|
Check to see if a LOB is open |
|
|
Determine if a given LOB is temporary |
|
|
Load a LOB from a |
|
|
Assign one LOB locator to another |
|
|
Check to see if a LOB locator is initialized |
|
|
Open a LOB |
|
|
Read a portion of a LOB. This function must be used for LOBs of size greater than 4 GB. |
|
|
Store the user-specified content type string of the SecureFile |
|
|
Enable option settings for existing and newly created SecureFiles |
|
|
Truncate a LOB. This function must be used for LOBs of size greater than 4 GB. |
|
|
Write into a LOB. This function must be used for LOBs of size greater than 4 GB. |
|
|
Write data beginning at the end of a LOB. This function must be used for LOBs of size greater than 4 GB. |
Note the following for parameters in the OCI LOB calls:
For fixed-width client-side character sets, the offset and amount parameters are always in characters for CLOBs and NCLOBs, and in bytes for BLOBs and BFILEs.
For varying-width client-side character sets, these rules generally apply:
Amount (amtp) parameter - When the amount parameter refers to the server-side LOB, the amount is in characters. When the amount parameter refers to the client-side buffer, the amount is in bytes.
For more information, see individual LOB calls, such as OCILobGetLength() (deprecated), OCILobGetLength2(), OCILobRead() (deprecated), OCILobRead2(), OCILobWrite() (deprecated), and OCILobWrite2().
Offset (offset) parameter - Regardless of whether the client-side character set is varying-width, the offset parameter is always in characters for CLOBs and NCLOBs and in bytes for BLOBs and BFILEs.
For many of the LOB operations, regardless of the client-side character set, the amount parameter is in characters for CLOBs and NCLOBs. These LOB operations include OCILobCopy2(), OCILobErase2(), OCILobGetLength2(), OCILobLoadFromFile2(), and OCILobTrim2(). All these operations refer to the amount of LOB data on the server.
A streaming operation means that the LOB is read or written in pieces. Streaming can be implemented using a polling mechanism or by registering a user-defined callback.
sword OCIDurationBegin ( OCIEnv *env,
OCIError *err,
const OCISvcCtx *svc,
OCIDuration parent,
OCIDuration *duration );
Pass as a NULL pointer.
The OCI error handle. If there is an error, it is recorded in err and this function returns OCI_ERROR. Diagnostic information can be obtained by calling OCIErrorGet().
An OCI service context handle. Must be non-NULL.
The duration number of the parent duration. It is one of these:
An identifier unique to the newly created user duration.
This function starts a user duration. In release 8.1 or later, user durations can be used when creating temporary LOBs. A user can have multiple active user durations simultaneously. The user durations do not have to be nested. The duration parameter is used to return a number that uniquely identifies the duration created by this call.
See Also:
"Temporary LOB Durations"
sword OCIDurationEnd ( OCIEnv *env,
OCIError *err,
const OCISvcCtx *svc,
OCIDuration duration );
Pass as a NULL pointer.
The OCI error handle. If there is an error, it is recorded in err and this function returns OCI_ERROR. Diagnostic information can be obtained by calling OCIErrorGet().
OCI service context. This should be passed as NULL for cartridge services.
A number to identify the user duration.
This function terminates a user duration. Temporary LOBs that are allocated for the user duration are freed.
See Also:
"Temporary LOB Durations"
sword OCILobAppend ( OCISvcCtx *svchp,
OCIError *errhp,
OCILobLocator *dst_locp,
OCILobLocator *src_locp );
The service context handle.
An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.
An internal LOB locator uniquely referencing the destination LOB. This locator must have been a locator that was obtained from the server specified by svchp.
An internal LOB locator uniquely referencing the source LOB. This locator must have been a locator that was obtained from the server specified by svchp.
Appends a LOB value at the end of another LOB as specified. The data is copied from the source to the end of the destination. The source and destination LOBs must exist. The destination LOB is extended to accommodate the newly written data. It is an error to extend the destination LOB beyond the maximum length allowed (4 Gigabytes (GB)) or to try to copy from a NULL LOB.
The source and the destination LOB locators must be of the same type (that is, they must both be BLOBs or both be CLOBs). LOB buffering must not be enabled for either type of locator. This function does not accept a BFILE locator as the source or the destination.
It is not mandatory that you wrap this LOB operation inside the open or close calls. If you did not open the LOB before performing this operation, then the functional and domain indexes on the LOB column are updated during this call. However, if you did open the LOB before performing this operation, then you must close it before you commit your transaction. When an internal LOB is closed, it updates the functional and domain indexes on the LOB column.
If you do not wrap your LOB operations inside the open or close API, then the functional and domain indexes are updated each time you write to the LOB. This can adversely affect performance. If you have functional or domain indexes, Oracle recommends that you enclose write operations to the LOB within the open or close statements.
OCILobTrim() (deprecated), OCILobTrim2(), OCILobWrite() (deprecated), OCILobWrite2(), OCILobCopy() (deprecated), OCILobCopy2(), OCIErrorGet(), OCILobWriteAppend() (deprecated), OCILobWriteAppend2()
Reads LOB data for multiple locators in one round-trip. This function can be used for LOBs of size greater than or less than 4 GB.
sword OCILobArrayRead ( OCISvcCtx *svchp,
OCIError *errhp,
ub4 *array_iter,
OCILobLocator **locp_arr,
oraub8 *byte_amt_arr,
oraub8 *char_amt_arr,
oraub8 *offset_arr,
void **bufp_arr,
oraub8 bufl_arr,
ub1 piece,
void *ctxp,
OCICallbackLobArrayRead (cbfp)
(
void *ctxp,
ub4 array_iter,
const void *bufp,
oraub8 lenp,
ub1 piecep
void **changed_bufpp,
oraub8 *changed_lenp
)
ub2 csid,
ub1 csfrm );
The service context handle.
An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.
IN - This parameter indicates the size of the LOB locator array. For polling this is relevant only for the first call and is ignored in subsequent calls.
OUT - In polling mode, this parameter indicates the array index of the element read from.
An array of LOB or BFILE locators.
An array of oraub8 variables. The array size must be the same as the locator array size. The entries correspond to the amount in bytes for the locators.
IN - The number of bytes to read from the database. Used for BLOB and BFILE always. For CLOB and NCLOB, it is used only when the corresponding value in char_amt_arr is zero.
OUT - The number of bytes read into the user buffer.
An array of oraub8 variables. The array size must be the same as the locator array size. The entries correspond to the amount in characters for the locators.
IN - The maximum number of characters to read into the user buffer. Ignored for BLOB and BFILE.
OUT - The number of characters read into the user buffer. Undefined for BLOB and BFILE.
An array of oraub8 variables. The array size must be the same as the locator array size. For character LOBs (CLOBs, NCLOBs) it is the number of characters from the beginning of the LOB; for binary LOBs or BFILEs, it is the number of bytes. The first position is 1.
An array of pointers to buffers into which the piece is read. The array size must be the same as the locator array size.
An array of oraub8 variables indicating the buffer lengths for the buffer array. The array size must be the same as the locator array size.
OCI_ONE_PIECE - The call never assumes polling. If the amount indicated is more than the buffer length, then the buffer is filled as much as possible.
For polling, pass OCI_FIRST_PIECE the first time and OCI_NEXT_PIECE in subsequent calls. OCI_FIRST_PIECE should be passed while using the callback.
The context pointer for the callback function. Can be NULL.
A callback that can be registered to be called for each piece. If this is NULL, then OCI_NEED_DATA is returned for each piece.
The callback function must return OCI_CONTINUE for the read to continue. If any other error code is returned, the LOB read is terminated.
The context for the callback function. Can be NULL.
The index of the element read from.
A buffer pointer for the piece.
The length in bytes of the current piece in bufp.
Which piece: OCI_FIRST_PIECE, OCI_NEXT_PIECE, or OCI_LAST_PIECE.
The callback function can put the address of a new buffer if it prefers to use a new buffer for the next piece to read. The default old buffer bufp is used if this parameter is set to NULL.
Length of the new buffer, if provided.
The character set ID of the buffer data. If this value is 0, then csid is set to the client's NLS_LANG or NLS_CHAR value, depending on the value of csfrm. It is never assumed to be the server character set, unless the server and client have the same settings.
The character set form of the buffer data. The csfrm parameter must be consistent with the type of the LOB.
The csfrm parameter has two possible nonzero values:
The default value is SQLCS_IMPLICIT. If csfrm is not specified, the default is assumed.
It is an error to try to read from a NULL LOB or BFILE.
Note:
When reading or writing LOBs, the character set form (csfrm) specified should match the form of the locator itself.For BFILEs, the operating system file must exist on the server, and it must have been opened by OCILobFileOpen() or OCILobOpen() using the input locator. The Oracle Database must have permission to read the operating system file, and the user must have read permission on the directory object.
When you use the polling mode for OCILobArrayRead(), the first call must specify values for offset_arr and amt_arr, but on subsequent polling calls to OCILobArrayRead(), you need not specify these values.
If the LOB is a BLOB, the csid and csfrm parameters are ignored.
Note:
To terminate anOCILobArrayRead() operation and free the statement handle, use the OCIBreak() call.The following points apply to reading LOB data in streaming mode:
When you use polling mode, be sure to specify the char_amt_arr and byte_amt_arr and offset_arr parameters only in the first call to OCILobArrayRead(). On subsequent polling calls, these parameters are ignored. If both byte_amt_arr and char_amt_arr are set to point to zero and OCI_FIRST_PIECE is passed, then polling mode is assumed and data is read to the end of the LOB. On output, byte_amt_arr gives the number of bytes read in the current piece. For CLOBs and NCLOBs, char_amt_arr gives the number of characters read in the current piece.
When you use callbacks, the lenp parameter, which is input to the callback, indicates how many bytes are filled in the buffer. Check the lenp parameter during your callback processing, because the entire buffer may not be filled with data.
When you use polling, examine the byte_amt_arr parameter to see how much the buffer is filled for the current piece. For CLOBs and NCLOBs, char_amt_arr returns the number of characters read in the buffer as well.
To read data in UTF-16 format, set the csid parameter to OCI_UTF16ID. If the csid parameter is set, it overrides the NLS_LANG environment variable.
See Also:
"PL/SQL REF CURSORs and Nested Tables in OCI" for additional information on Unicode format
Oracle Database SecureFiles and Large Objects Developer's Guide for a description of BFILEs
The demonstration programs included with your Oracle Database installation for a code sample showing the use of LOB reads and writes.
"Runtime Data Allocation and Piecewise Operations in OCI" for general information about piecewise OCI operations
Writes LOB data for multiple locators in one round-trip. This function can be used for LOBs of size greater than or less than 4 GB.
sword OCILobArrayWrite ( OCISvcCtx *svchp,
OCIError *errhp,
ub4 *array_iter,
OCILobLocator **locp_arr,
oraub8 *byte_amt_arr,
oraub8 *char_amt_arr,
oraub8 *offset_arr,
void **bufp_arr,
oraub8 *bufl_arr,
ub1 piece,
void *ctxp,
OCICallbackLobArrayWrite (cbfp)
(
void *ctxp,
ub4 array_iter,
void *bufp,
oraub8 *lenp,
ub1 *piecep
void **changed_bufpp,
oraub8 *changed_lenp
)
ub2 csid,
ub1 csfrm );
The service context handle.
An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.
IN - This parameter indicates the size of the LOB locator array. For polling this is relevant only for the first call and is ignored in subsequent calls.
OUT - In polling mode this parameter indicates the array index of the element just written to.
An array of LOB locators.
An array of pointers to oraub8 variables. The array size must be the same as the locator array size. The entries correspond to the amount in bytes for the locators.
IN - The number of bytes to write to the database. Always used for BLOB. For CLOB and NCLOB it is used only when char_amt_arr is zero.
OUT - The number of bytes written to the database.
An array of pointers to oraub8 variables. The array size must be the same as the locator array size. The entries correspond to the amount in characters for the locators.
IN - The maximum number of characters to write to the database. Ignored for BLOB.
OUT - The number of characters written to the database. Undefined for BLOB.
An array of pointers to oraub8 variables. The array size must be the same as the locator array size. Each entry in the array is the absolute offset from the beginning of the LOB value. For character LOBs (CLOBs, NCLOBs), it is the number of characters from the beginning of the LOB; for BLOBs, it is the number of bytes. The first position is 1.
An array of pointers to buffers into which the pieces for the locators are written. The array size must be the same as the locator array size.
An array of oraub8 variables indicating the buffer lengths for the buffer array. The array size must be the same as the locator array size.
Note:
This parameter assumes an 8-bit byte. If your operating system uses a longer byte, you must adjust the value ofbufl_arr accordingly.Which piece of the buffer is being written. The default value for this parameter is OCI_ONE_PIECE, indicating that the buffer is written in a single piece.
The following other values are also possible for piecewise or callback mode: OCI_FIRST_PIECE, OCI_NEXT_PIECE, and OCI_LAST_PIECE.
The context for the callback function. Can be NULL.
A callback that can be registered to be called for each piece. If this is NULL, then OCI_NEED_DATA is returned for each piece. The callback function must return OCI_CONTINUE for the write to continue. If any other error code is returned, the LOB write is terminated.
The callback takes the following parameters:
The context for the callback function. Can be NULL.
The index of the element written to.
A buffer pointer for the piece. This is the same as the bufp passed as an input to the OCILobArrayWrite() routine.
The length (in bytes) of the data in the buffer (IN), and the length (in bytes) of the current piece in bufp (OUT).
Which piece: OCI_NEXT_PIECE or OCI_LAST_PIECE.
The callback function can put the address of a new buffer if it prefers to use a new buffer for the next piece to read. The default old buffer bufp is used if this parameter is set to NULL.
Length of the new buffer, if provided.
The character set ID of the data in the buffer. If this value is 0, then csid is set to the client's NLS_LANG or NLS_CHAR value, depending on the value of csfrm.
The character set form of the buffer data. The csfrm parameter must be consistent with the type of the LOB.
The csfrm parameter has two possible nonzero values:
The default value is SQLCS_IMPLICIT.
If LOB data exists, it is overwritten with the data stored in the buffer. The buffers can be written to the LOBs in a single piece with this call, or the buffers can be provided piecewise using callbacks or a standard polling method.
Note:
When you read or write LOBs, specify a character set form (csfrm) that matches the form of the locator itself.
The parameters piece, csid, and csfrm are the same for all locators of the array.
When you use the polling mode for OCILobArrayWrite(), the first call must specify values for offset_arr, byte_amt_arr, and char_amt_arr, but on subsequent polling calls to OCILobArrayWrite(), you need not specify these values.
If the value of the piece parameter is OCI_FIRST_PIECE, data may need to be provided through callbacks or polling.
If a callback function is defined in the cbfp parameter, then this callback function is invoked to get the next piece after a piece is written to the pipe. Each piece is written from bufp_arr. If no callback function is defined, then OCILobArrayWrite() returns the OCI_NEED_DATA error code. The application must call OCILobArrayWrite() again to write more pieces of the LOBs. In this mode, the buffer pointer and the length can be different in each call if the pieces are of different sizes and from different locations.
A piece value of OCI_LAST_PIECE terminates the piecewise write, regardless of whether the polling or callback method is used.
If the amount of data passed to the database (through either input mechanism) is less than the amount specified by the byte_amt_arr or the char_amt_arr parameter, an ORA-22993 error is returned.
This function is valid for internal LOBs only. BFILEs are not valid, because they are read-only. If the LOB is a BLOB, the csid and csfrm parameters are ignored.
If both byte_amt_arr and char_amt_arr are set to point to zero amount and OCI_FIRST_PIECE is given as input, then polling mode is assumed and data is written until you specify OCI_LAST_PIECE. For CLOBs and NCLOBs, byte_amt_arr and char_amt_arr return the data written by each piece in terms of number of bytes and number of characters respectively. For BLOBs, byte_amt_arr returns the number of bytes written by each piece, whereas char_amt_arr is undefined on output.
To write data in UTF-16 format, set the csid parameter to OCI_UTF16ID. If the csid parameter is set, it overrides the NLS_LANG environment variable.
It is not mandatory that you wrap this LOB operation inside the open or close calls. If you did not open the LOB before performing this operation, then the functional and domain indexes on the LOB column are updated during this call. However, if you did open the LOB before performing this operation, then you must close it before you commit your transaction. When an internal LOB is closed, it updates the functional and domain indexes on the LOB column.
If you do not wrap your LOB operations inside the open or close API, then the functional and domain indexes are updated each time you write to the LOB. This can adversely affect performance. If you have functional or domain indexes, Oracle recommends that you enclose write operations to the LOB within the open or close statements.
See Also:
"PL/SQL REF CURSORs and Nested Tables in OCI" for additional information on Unicode format
The demonstration programs included with your Oracle Database installation for a code sample showing the use of LOB reads and writes.
"Runtime Data Allocation and Piecewise Operations in OCI" for general information about piecewise OCI operations
sword OCILobAssign ( OCIEnv *envhp,
OCIError *errhp,
const OCILobLocator *src_locp,
OCILobLocator **dst_locpp );
OCI environment handle.
An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.
LOB or BFILE locator to copy from.
LOB or BFILE locator to copy to. The caller must have allocated space for the destination locator by calling OCIDescriptorAlloc().
Assign source locator to destination locator. After the assignment, both locators refer to the same LOB value. For internal LOBs, the source locator's LOB value gets copied to the destination locator's LOB value only when the destination locator gets stored in the table. Therefore, issuing a flush of the object containing the destination locator copies the LOB value.
OCILobAssign() cannot be used for temporary LOBs; it generates an OCI_INVALID_HANDLE error. For temporary LOBs, use OCILobLocatorAssign().
For BFILEs, only the locator that refers to the file is copied to the table. The operating system file itself is not copied.
It is an error to assign a BFILE locator to an internal LOB locator, and vice versa.
If the source locator is for an internal LOB that was enabled for buffering, and the source locator has been used to modify the LOB data through the LOB buffering subsystem, and the buffers have not been flushed since the write, then the source locator may not be assigned to the destination locator. This is because only one locator for each LOB can modify the LOB data through the LOB buffering subsystem.
The value of the input destination locator must have been allocated with a call to OCIDescriptorAlloc(). For example, assume the following declarations:
OCILobLocator *source_loc = (OCILobLocator *) 0; OCILobLocator *dest_loc = (OCILobLocator *) 0;
Example 17-1 shows how an application could allocate the source_loc locator.
Example 17-1 Allocating a source_loc Source Locator
if (OCIDescriptorAlloc((void *) envhp, (void **) &source_loc,
(ub4) OCI_DTYPE_LOB, (size_t) 0, (void **) 0))
handle_error;
Assume that it then selects a LOB from a table into the source_loc to initialize it. The application must allocate the destination locator, dest_loc, before issuing the OCILobAssign() call to assign the value of source_loc to dest_loc, as shown shown in Example 17-2.
sword OCILobCharSetForm ( OCIEnv *envhp,
OCIError *errhp,
const OCILobLocator *locp,
ub1 *csfrm );
OCI environment handle.
An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.
LOB locator for which to get the character set form.
Character set form of the input LOB locator. If the input locator, locp, is for a BLOB or a BFILE, csfrm is set to 0 because there is no concept of a character set for binary LOBs and BFILEs. The caller must allocate space for csfrm (a ub1).
The csfrm parameter has two possible nonzero values:
Returns the character set form of the input CLOB or NCLOB locator in the csfrm output parameter.
sword OCILobCharSetId ( OCIEnv *envhp,
OCIError *errhp,
const OCILobLocator *locp,
ub2 *csid );
OCI environment handle.
An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.
LOB locator for which to get the character set ID.
Database character set ID of the input LOB locator. If the input locator is for a BLOB or a BFILE, csid is set to 0 because there is no concept of a character set for binary LOBs or binary files. The caller must allocate space for the csid ub2.
Returns the character set ID of the input CLOB or NCLOB locator in the csid output parameter.
The service context handle.
An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.
The LOB to close. The locator can refer to an internal or external LOB.
Closes a previously opened internal or external LOB. No error is returned if the BFILE exists but is not opened. An error is returned if the internal LOB is not open.
Closing a LOB requires a round-trip to the server for both internal and external LOBs. For internal LOBs, close triggers other code that relies on the close call and for external LOBs (BFILEs), close actually closes the server-side operating system file.
It is not mandatory that you wrap all LOB operations inside the open or close calls. However, if you open a LOB, then you must close it before you commit your transaction. When an internal LOB is closed, it updates the functional and domain indexes on the LOB column. It is an error to commit the transaction before closing all opened LOBs that were opened by the transaction.
When the error is returned, the LOB is no longer marked as open, but the transaction is successfully committed. Hence, all the changes made to the LOB and non-LOB data in the transaction are committed, but the domain and function-based indexing are not updated. If this happens, rebuild your functional and domain indexes on the LOB column.
If you do not wrap your LOB operations inside the open or close API, then the functional and domain indexes are updated each time you write to the LOB. This can adversely affect performance, so if you have functional or domain indexes, Oracle recommends that you enclose write operations to the LOB within the open or close statements.
See Also:
"Functions for Opening and Closing LOBs"Copies all or a portion of a LOB value into another LOB value. This function must be used for LOBs of size greater than 4 GB. You can also use this function for LOBs smaller than 4 GB.
sword OCILobCopy2 ( OCISvcCtx *svchp,
OCIError *errhp,
OCILobLocator *dst_locp,
OCILobLocator *src_locp,
oraub8 amount,
oraub8 dst_offset,
oraub8 src_offset );
The service context handle.
An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.
An internal LOB locator uniquely referencing the destination LOB. This locator must have been a locator that was obtained from the server specified by svchp.
An internal LOB locator uniquely referencing the source LOB. This locator must have been a locator that was obtained from the server specified by svchp.
The number of characters for CLOBs or NCLOBs or the number of bytes for BLOBs to be copied from the source LOB to the destination LOB. The maximum value accepted by this parameter is UB8MAXVAL (18446744073709551615). Specifying UB8MAXVAL also indicates that the entire source LOB will be copied to the destination LOB using the specified source and destination offsets.
This is the absolute offset for the destination LOB. For character LOBs, it is the number of characters from the beginning of the LOB at which to begin writing. For binary LOBs, it is the number of bytes from the beginning of the LOB from which to begin writing. The offset starts at 1.
This is the absolute offset for the source LOB. For character LOBs, it is the number of characters from the beginning of the LOB. For binary LOBs, it is the number of bytes. Starts at 1.
Copies all or a portion of an internal LOB value into another internal LOB as specified. The data is copied from the source to the destination. The source (src_locp) and the destination (dst_locp) LOBs must exist.
Copying a complete SecureFile in a column or partition with deduplicate enabled, to a LOB in the same column or partition, causes the copy to be deduplicated.
If the data exists at the destination's start position, it is overwritten with the source data. If the destination's start position is beyond the end of the current data, zero-byte fillers (for BLOBs) or spaces (for CLOBs) are written into the destination LOB from the end of the current data to the beginning of the newly written data from the source. The destination LOB is extended to accommodate the newly written data if it extends beyond the current length of the destination LOB. It is an error to extend the destination LOB beyond the maximum length allowed (that is, 4 gigabytes) or to try to copy from a NULL LOB. Use OCILobCopy2() for LOBs of size greater than 4 GB.
Both the source and the destination LOB locators must be of the same type (that is, they must both be BLOBs or both be CLOBs). LOB buffering must not be enabled for either locator.
This function does not accept a BFILE locator as the source or the destination.
It is not mandatory that you wrap this LOB operation inside the open or close calls. If you did not open the LOB before performing this operation, then the functional and domain indexes on the LOB column are updated during this call. However, if you did open the LOB before performing this operation, then you must close it before you commit your transaction. When an internal LOB is closed, it updates the functional and domain indexes on the LOB column.
If you do not wrap your LOB operations inside the open or close API, then the functional and domain indexes are updated each time you write to the LOB. This can adversely affect performance. If you have functional or domain indexes, Oracle recommends that you enclose write operations to the LOB within the open or close statements.
Note:
You can call OCILobGetLength2() to determine the length of the source LOB.
sword OCILobCreateTemporary(OCISvcCtx *svchp,
OCIError *errhp,
OCILobLocator *locp,
ub2 csid,
ub1 csfrm,
ub1 lobtype,
boolean cache,
OCIDuration duration);
The OCI service context handle.
An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.
A locator that points to the temporary LOB. You must allocate the locator using OCIDescriptorAlloc() before passing it to this function. It does not matter whether this locator points to a LOB; the temporary LOB gets overwritten either way.
The LOB character set ID. For Oracle8i or later, pass as OCI_DEFAULT.
The LOB character set form of the buffer data. The csfrm parameter has two possible nonzero values:
SQLCS_IMPLICIT - Database character set ID, to create a CLOB. OCI_DEFAULT can also be used to implicitly create a CLOB.
The default value is SQLCS_IMPLICIT.
The type of LOB to create. Valid values include:
OCI_TEMP_BLOB - For a temporary BLOB
OCI_TEMP_CLOB - For a temporary CLOB or NCLOB
Pass TRUE if the temporary LOB should be read into the cache; pass FALSE if it should not. The default is FALSE for NOCACHE functionality.
The duration of the temporary LOB. The following are valid values:
OCI_DURATION_SESSION
OCI_DURATION_CALL
This function creates a temporary LOB and its corresponding index in the user's temporary tablespace.
When this function is complete, the locp parameter points to an empty temporary LOB whose length is zero.
The lifetime of the temporary LOB is determined by the duration parameter. At the end of its duration the temporary LOB is freed. An application can free a temporary LOB sooner with the OCILobFreeTemporary() call.
If the LOB is a BLOB, the csid and csfrm parameters are ignored.
See Also:
"Temporary LOB Support" for more information about temporary LOBs and their durationsThe service context handle.
An error handle that you can pass to OCIErrorGet() or diagnostic information when there is an error.
An internal LOB locator uniquely referencing the LOB.
Disables LOB buffering for the input internal LOB locator. The next time data is read from or written to the LOB through the input locator, the LOB buffering subsystem is not used. Note that this call does not implicitly flush the changes made in the buffering subsystem. The user must explicitly call OCILobFlushBuffer() to do this.
This function does not accept a BFILE locator.
The service context handle.
An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.
An internal LOB locator uniquely referencing the LOB.
Enables LOB buffering for the input internal LOB locator. The next time data is read from or written to the LOB through the input locator, the LOB buffering subsystem is used.
If LOB buffering is enabled for a locator and that locator is passed to one of these routines, an error is returned: OCILobAppend(), OCILobCopy() (deprecated), OCILobCopy2(), OCILobErase() (deprecated), OCILobErase2(), OCILobGetLength() (deprecated), OCILobGetLength2(), OCILobLoadFromFile() (deprecated), OCILobLoadFromFile2(), OCILobTrim() (deprecated), OCILobTrim2(), OCILobWriteAppend() (deprecated), or OCILobWriteAppend2().
This function does not accept a BFILE locator.
OCILobDisableBuffering(), OCIErrorGet(), OCILobWrite() (deprecated), OCILobWrite2(), OCILobRead() (deprecated), OCILobRead2(), OCILobFlushBuffer(), OCILobWriteAppend() (deprecated), OCILobWriteAppend2()
Erases a specified portion of the internal LOB data starting at a specified offset. This function must be used for LOBs of size greater than 4 GB. You can also use this function for LOBs smaller than 4 GB.
sword OCILobErase2 ( OCISvcCtx *svchp,
OCIError *errhp,
OCILobLocator *locp,
oraub8 *amount,
oraub8 offset );
The service context handle.
An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.
An internal LOB locator that uniquely references the LOB. This locator must have been a locator that was obtained from the server specified by svchp.
The number of characters for CLOBs or NCLOBs, or bytes for BLOBs, to erase. On IN, the value signifies the number of characters or bytes to erase. On OUT, the value identifies the actual number of characters or bytes erased.
Absolute offset in characters for CLOBs or NCLOBs, or bytes for BLOBs, from the beginning of the LOB value from which to start erasing data. Starts at 1.
The actual number of characters or bytes erased is returned. For BLOBs, erasing means that zero-byte fillers overwrite the existing LOB value. For CLOBs, erasing means that spaces overwrite the existing LOB value.
This function is valid only for internal LOBs; BFILEs are not allowed.
It is not mandatory that you wrap this LOB operation inside the open or close calls. If you did not open the LOB before performing this operation, then the functional and domain indexes on the LOB column are updated during this call. However, if you did open the LOB before performing this operation, then you must close it before you commit your transaction. When an internal LOB is closed, it updates the functional and domain indexes on the LOB column.
If you do not wrap your LOB operations inside the open or close API, then the functional and domain indexes are updated each time you write to the LOB. This can adversely affect performance. If you have functional or domain indexes, Oracle recommends that you enclose write operations to the LOB within the open or close statements.
The service context handle.
An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.
A pointer to a BFILE locator that refers to the BFILE to be closed.
Closes a previously opened BFILE. It is an error if this function is called for an internal LOB. No error is returned if the BFILE exists but is not opened.
This function is only meaningful the first time it is called for a particular BFILE locator. Subsequent calls to this function using the same BFILE locator have no effect.
See Also:
Oracle Database SecureFiles and Large Objects Developer's Guide for a description ofBFILEsThe service context handle.
An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.
Closes all open BFILEs on a given service context.
See Also:
Oracle Database SecureFiles and Large Objects Developer's Guide for a description ofBFILEs
sword OCILobFileExists ( OCISvcCtx *svchp,
OCIError *errhp,
OCILobLocator *filep,
boolean *flag );
The OCI service context handle.
An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.
Pointer to the BFILE locator that refers to the file.
Returns TRUE if the BFILE exists on the server; FALSE if it does not.
Checks to see if the BFILE exists on the server's file system. It is an error to call this function for an internal LOB.
See Also:
Oracle Database SecureFiles and Large Objects Developer's Guide for a description ofBFILEs
sword OCILobFileGetName ( OCIEnv *envhp,
OCIError *errhp,
const OCILobLocator *filep,
OraText *dir_alias,
ub2 *d_length,
OraText *filename,
ub2 *f_length );
OCI environment handle.
An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.
BFILE locator for which to get the directory object and file name.
Buffer into which the directory object name is placed. This can be in UTF-16. You must allocate enough space for the directory object name. The maximum length for the directory object is 30 bytes.
Serves the following purposes (can be in code point for Unicode, or bytes):
IN: length of the input dir_alias string
OUT: length of the returned dir_alias string
Buffer into which the file name is placed. You must allocate enough space for the file name. The maximum length for the file name is 255 bytes.
Serves the following purposes (in number of bytes):
IN: length of the input filename buffer
OUT: length of the returned filename string
Returns the directory object and file name associated with this BFILE locator. The environment handle determines whether it is in Unicode. It is an error to call this function for an internal LOB.
See Also:
Oracle Database SecureFiles and Large Objects Developer's Guide for a description ofBFILEs
sword OCILobFileIsOpen ( OCISvcCtx *svchp,
OCIError *errhp,
OCILobLocator *filep,
boolean *flag );
The OCI service context handle.
An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.
Pointer to the BFILE locator being examined.
Returns TRUE if the BFILE was opened using this particular locator; returns FALSE if it was not.
Checks to see if a file on the server was opened with the filep BFILE locator. It is an error to call this function for an internal LOB.
If the input BFILE locator was never passed to the OCILobFileOpen() or OCILobOpen() command, the file is considered not to be opened by this locator. However, a different locator may have the file open. Openness is associated with a particular locator.
See Also:
Oracle Database SecureFiles and Large Objects Developer's Guide for a description ofBFILEsThe service context handle.
An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.
The BFILE to open. It is an error if the locator does not refer to a BFILE.
Mode in which to open the file. The only valid mode is OCI_FILE_READONLY.
Opens a BFILE on the file system of the server. The BFILE can be opened for read-only access. BFILEs can not be written through Oracle Database. It is an error to call this function for an internal LOB.
This function is only meaningful the first time it is called for a particular BFILE locator. Subsequent calls to this function using the same BFILE locator have no effect.
See Also:
Oracle Database SecureFiles and Large Objects Developer's Guide for a description ofBFILEs
sword OCILobFileSetName ( OCIEnv *envhp,
OCIError *errhp,
OCILobLocator **filepp,
const OraText *dir_alias,
ub2 d_length,
const OraText *filename,
ub2 f_length );
OCI environment handle. Contains the UTF-16 setting.
An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.
Pointer to the BFILE locator for which to set the directory object and file name.
Buffer that contains the directory object name (must be in the encoding specified by the charset parameter of a previous call to OCIEnvNlsCreate()) to set in the BFILE locator.
Length (in bytes) of the input dir_alias parameter.
Buffer that contains the file name (must be in the encoding specified by the charset parameter of a previous call to OCIEnvNlsCreate()) to set in the BFILE locator.
Length (in bytes) of the input filename parameter.
It is an error to call this function for an internal LOB.
See Also:
Oracle Database SecureFiles and Large Objects Developer's Guide for a description ofBFILEsThe service context handle.
An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.
An internal locator uniquely referencing the LOB.
When this flag is set to OCI_LOB_BUFFER_FREE, the buffer resources for the LOB are freed after the flush. See the Comments section.
Flushes to the server changes made to the buffering subsystem that are associated with the LOB referenced by the input locator. This routine actually writes the data in the buffer to the LOB in the database. LOB buffering must have been enabled for the input LOB locator.
The flush operation, by default, does not free the buffer resources for reallocation to another buffered LOB operation. To free the buffer explicitly, you can set the flag parameter to OCI_LOB_BUFFER_FREE.
If the client application intends to read the buffer value after the flush and knows in advance that the current value in the buffer is the desired value, there is no need to reread the data from the server.
The effects of freeing the buffer are mostly transparent to the user, except that the next access to the same range in the LOB involves a round-trip to the server, and there is an added cost for acquiring buffer resources and initializing the buffer with the data read from the LOB. This option is intended for client environments that have low on-board memory.
OCILobEnableBuffering(), OCIErrorGet(), OCILobWrite() (deprecated), OCILobWrite2(), OCILobRead() (deprecated), OCILobRead2(), OCILobDisableBuffering(), OCILobWriteAppend() (deprecated), OCILobWriteAppend2()
The OCI service context handle.
An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.
A locator uniquely referencing the LOB to be freed.
This function frees the contents of the temporary LOB to which this locator points. Note that the locator itself is not freed until OCIDescriptorFree() is called.
This function returns an error if the LOB locator passed in the locp parameter does not point to a temporary LOB, possibly because the LOB locator:
Points to a permanent LOB
Pointed to a temporary LOB that has been freed
Has never pointed to anything
sword OCILobGetChunkSize ( OCISvcCtx *svchp,
OCIError *errhp,
OCILobLocator *locp,
ub4 *chunk_size );
The service context handle.
An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.
The internal LOB for which to get the usable chunk size.
For LOBs with storage parameter BASICFILE, the amount of a chunk's space that is used to store the internal LOB value. This is the amount that users should use when reading or writing the LOB value. If possible, users should start their writes at chunk boundaries, such as the beginning of a chunk, and write a chunk at a time.
The chunk_size parameter is returned in terms of bytes for BLOBs, CLOBs, and NCLOBs.
For LOBs with storage parameter SECUREFILE, chunk_size is an advisory size and is provided for backward compatibility.
When creating a table that contains an internal LOB, the user can specify the chunking factor, which can be a multiple of Oracle Database blocks. This corresponds to the chunk size used by the LOB data layer when accessing and modifying the LOB value. Part of the chunk is used to store system-related information, and the rest stores the LOB value. This function returns the amount of space used in the LOB chunk to store the LOB value. Performance is improved if the application issues read or write requests using a multiple of this chunk size. For writes, there is an added benefit because LOB chunks are versioned and, if all writes are done on a chunk basis, no extra versioning is done or duplicated. Users could batch up the write until they have enough for a chunk instead of issuing several write calls for the same chunk.
See Also:
"Improving LOB Read/Write Performance"OCIErrorGet(), OCILobGetStorageLimit(), OCILobRead() (deprecated), OCILobRead2(), OCILobAppend(), OCILobCopy() (deprecated), OCILobCopy2(), OCILobWrite() (deprecated), OCILobWrite2(), OCILobWriteAppend() (deprecated), OCILobWriteAppend2()
sword OCILobGetContentType ( OCIEnv *envhp,
OCISvcCtx *svchp,
OCIError *errhp,
OCILobLocator *lobp,
oratext *contenttypep,
ub4 *contenttypelenp,
ub4 mode );
The environment handle.
The service context handle.
An error handle that can be passed to OCIErrorGet() for diagnostic information when there is an error.
A LOB locator that uniquely references a LOB.
Pointer to the buffer where the content type is stored after successful execution. You must allocate the buffer before calling this function. The size of the allocated buffer must be >= OCI_LOB_CONTENTTYPE_MAXSIZE.
Set this field to the size of contenttypep buffer. After the call successfully executes, this field holds the size of the contenttypep returned.
For future use. Pass zero now.
This function only works on SecureFiles. If lobp is not a SecureFile, then the error SECUREFILE_WRONGTYPE is returned. If lobp is buffered, a temporary LOB, or an abstract LOB, then the error SECUREFILE_BADLOB is returned.
If the SecureFile does not have a contenttype associated with it, the contenttype length (contenttypelenp) is returned as 0 without modifying the buffer contenttypep.
The maximum possible size of the ContentType string is defined as:
#define OCI_LOB_CONTENTTYPE_MAXSIZE 128
The ContentType is ASCII (that is, 1-byte/7-bit UTF8).
Gets the length of a LOB. This function must be used for LOBs of size greater than 4 GB. You can also use this function for LOBs smaller than 4 GB.
sword OCILobGetLength2 ( OCISvcCtx *svchp,
OCIError *errhp,
OCILobLocator *locp,
oraub8 *lenp );
The service context handle.
An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.
A LOB locator that uniquely references the LOB. For internal LOBs, this locator must have been a locator that was obtained from the server specified by svchp. For BFILEs, the locator can be set by OCILobFileSetName(), by a SELECT statement, or by OCIObjectPin().
On output, it is the length of the LOB if the LOB is not NULL. For character LOBs, it is the number of characters; for binary LOBs and BFILEs, it is the number of bytes in the LOB.
Gets the length of a LOB. If the LOB is NULL, the length is undefined. The length of a BFILE includes the EOF, if it exists. The length of an empty internal LOB is zero.
Regardless of whether the client-side character set is varying-width, the output length is in characters for CLOBs and NCLOBs, and in bytes for BLOBs and BFILEs.
Note:
Any zero-byte or space fillers in the LOB written by previous calls toOCILobErase2() or OCILobWrite2() are also included in the length count.Obtains the enabled settings corresponding to the given input option types for a given SecureFile LOB.
sword OCILobGetOptions ( OCISvcCtx *svchp,
OCIError *errhp,
OCILobLocator *locp,
ub4 option_types,
void *optionsp,
ub4 optionslenp,
ub4 mode );
The service context handle.
An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.
The LOB locator or BFILE locator that uniquely references the LOB or BFILE. This locator must have been obtained from the server specified by svchp.
The given option types that can be combined by a bit-wise inclusive OR (symbol "|"):
Compression - OCI_LOB_OPT_COMPRESS
Encryption - OCI_LOB_OPT_ENCRYPT
Deduplication - OCI_LOB_OPT_DEDUPLICATE
The current settings for each of the option types given. Possible values are:
OCI_LOB_OPT_COMPRESS_ON
OCI_LOB_OPT_ENCRYPT_ON
OCI_LOB_OPT_DEDUPLICATE_ON
The length of the value in optionsp.
Reserved for future use. Pass in 0.
You can only specify option types that have been enabled on the column. An error is returned when an attempt is made to get the value of an option type that is not enabled on the column. For example, if you have a LOB column with compression enabled, and you call OCILobGetOptions() with OCI_LOB_OPT_ENCRYPT set in the option_types parameter, an error occurs.
Note that the returned value is a ub4 pointer cast as a void pointer to allow for future expansion of option types and values. The optionslenp returned should be equal to sizeof(ub4).
sword OCILobGetStorageLimit ( OCISvcCtx *svchp,
OCIError *errhp,
OCILobLocator *locp,
oraub8 *limitp );
The service context handle.
An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.
A LOB locator that uniquely references the LOB. The locator must have been one that was obtained from the server specified by svchp.
The maximum length of the LOB (in bytes) that can be stored in the database.
Because block size ranges from 2 KB to 32 KB, the maximum LOB size ranges from 8 terabytes to 128 terabytes (TB) for LOBs.
See Also:
"Using LOBs of Size Greater than 4 GB"
sword OCILobIsEqual ( OCIEnv *envhp,
const OCILobLocator *x,
const OCILobLocator *y,
boolean *is_equal );
The OCI environment handle.
LOB locator to compare.
LOB locator to compare.
TRUE, if the LOB locators are equal; FALSE if they are not.
Compares the given LOB or BFILE locators for equality. Two LOB or BFILE locators are equal if and only if they both refer to the same LOB or BFILE value.
Two NULL locators are considered not equal by this function.
sword OCILobIsOpen ( OCISvcCtx *svchp,
OCIError *errhp,
OCILobLocator *locp,
boolean *flag );
The service context handle.
An error handle that can be passed to OCIErrorGet() for diagnostic information when there is an error.
Pointer to the LOB locator being examined. The locator can refer to an internal or external LOB.
Returns TRUE if the internal LOB is open or if the BFILE was opened using the input locator. Returns FALSE if it was not.
Checks to see if the internal LOB is open or if the BFILE was opened using the input locator.
If the input BFILE locator was never passed to OCILobOpen() or OCILobFileOpen(), the BFILE is considered not to be opened by this BFILE locator. However, a different BFILE locator may have opened the BFILE. Multiple opens can be performed on the same BFILE using different locators. In other words, openness is associated with a specific locator for BFILEs.
Openness is associated with the LOB, not with the locator. If locator1 opened the LOB, then locator2 also sees the LOB as open.
For internal LOBs, this call requires a server round-trip because it checks the state on the server to see if the LOB is open. For external LOBs (BFILEs), this call also requires a round-trip because the operating system file on the server side must be checked to see if it is open.
See Also:
"Functions for Opening and Closing LOBs"
sword OCILobIsTemporary(OCIEnv *envhp,
OCIError *errhp,
OCILobLocator *locp,
boolean *is_temporary);
The OCI environment handle.
An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.
The locator to test.
Returns TRUE if the LOB locator points to a temporary LOB; FALSE if it does not.
This function tests a locator to determine if it points to a temporary LOB. If so, is_temporary is set to TRUE. If not, is_temporary is set to FALSE.
Loads and copies all or a portion of the file into an internal LOB. This function must be used for LOBs of size greater than 4 GB. You can also use this function for LOBs smaller than 4 GB.
sword OCILobLoadFromFile2 ( OCISvcCtx *svchp,
OCIError *errhp,
OCILobLocator *dst_locp,
OCILobLocator *src_locp,
oraub8 amount,
oraub8 dst_offset,
oraub8 src_offset );
The service context handle.
An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.
A locator uniquely referencing the destination internal LOB, that may be of type BLOB, CLOB, or NCLOB.
A locator uniquely referencing the source BFILE.
The number of bytes to be loaded.
This is the absolute offset for the destination LOB. For character LOBs, it is the number of characters from the beginning of the LOB at which to begin writing. For binary LOBs, it is the number of bytes from the beginning of the LOB from which to begin reading. The offset starts at 1.
This is the absolute offset for the source BFILE. It is the number of bytes from the beginning of the BFILE. The offset starts at 1.
Loads and copies a portion or all of a BFILE value into an internal LOB as specified. The data is copied from the source BFILE to the destination internal LOB (BLOB or CLOB). No character set conversions are performed when copying the BFILE data to a CLOB or NCLOB. Also, when binary data is loaded into a BLOB, no character set conversions are performed. Therefore, the BFILE data must be in the same character set as the LOB in the database. No error checking is performed to verify this.
The source (src_locp) and the destination (dst_locp) LOBs must exist. If the data exists at the destination's start position, it is overwritten with the source data. If the destination's start position is beyond the end of the current data, zero-byte fillers (for BLOBs) or spaces (for CLOBs) are written into the destination LOB from the end of the data to the beginning of the newly written data from the source. The destination LOB is extended to accommodate the newly written data if it extends beyond the current length of the destination LOB.
It is an error to extend the destination LOB beyond the maximum length allowed (4 gigabytes) (see OCILobLoadFromFile2() to use for LOBs of size greater than 4 GB) or to try to copy from a NULL BFILE.
It is not mandatory that you wrap this LOB operation inside the open or close calls. If you did not open the LOB before performing this operation, then the functional and domain indexes on the LOB column are updated during this call. However, if you did open the LOB before performing this operation, then you must close it before you commit your transaction. When an internal LOB is closed, it updates the functional and domain indexes on the LOB column.
If you do not wrap your LOB operations inside the open or close API, then the functional and domain indexes are updated each time you write to the LOB. This can adversely affect performance. If you have functional or domain indexes, Oracle recommends that you enclose write operations to the LOB within the open or close statements.
sword OCILobLocatorAssign ( OCISvcCtx *svchp,
OCIError *errhp,
const OCILobLocator *src_locp,
OCILobLocator **dst_locpp );
The OCI service context handle.
An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.
The LOB or BFILE locator to copy from.
The LOB or BFILE locator to copy to. The caller must allocate space for the OCILobLocator by calling OCIDescriptorAlloc().
This call assigns the source locator to the destination locator. After the assignment, both locators refer to the same LOB data. For internal LOBs, the source locator's LOB data gets copied to the destination locator's LOB data only when the destination locator gets stored in the table. Therefore, issuing a flush of the object containing the destination locator copies the LOB data. For BFILEs, only the locator that refers to the operating system file is copied to the table; the operating system file is not copied.
Note that this call is similar to OCILobAssign(), but OCILobLocatorAssign() takes an OCI service handle pointer instead of an OCI environment handle pointer. Also, OCILobLocatorAssign() can be used for temporary LOBs, but OCILobAssign() cannot be used for temporary LOBs.
Note:
If theOCILobLocatorAssign() function fails, the target locator is not restored to its previous state. The target locator should not be used in subsequent operations unless it is reinitialized.If the destination locator is for a temporary LOB, the destination temporary LOB is freed before the source LOB locator is assignedto it.
If the source LOB locator refers to a temporary LOB, the destination is made into a temporary LOB too. The source and the destination are conceptually different temporary LOBs. In the OCI_DEFAULT mode, the source temporary LOB is deep copied, and a destination locator is created to refer to the new deep copy of the temporary LOB. Hence OCILobIsEqual() returns FALSE after the OCILobLocatorAssign() call. However, in the OCI_OBJECT mode, an optimization is made to minimize the number of deep copies, so the source and destination locators point to the same LOB until any modification is made through either LOB locator. Hence OCILobIsEqual() returns TRUE right after OCILobLocatorAssign() until the first modification. In both these cases, after the OCILobLocatorAssign(), any changes to the source or the destination do not reflect in the other (that is, destination or source) LOB. If you want the source and the destination to point to the same LOB and want your changes to reflect in the other, then you must use the equal sign to ensure that the two LOB locator pointers refer to the same LOB locator.
sword OCILobLocatorIsInit ( OCIEnv *envhp,
OCIError *errhp,
const OCILobLocator *locp,
boolean *is_initialized );
OCI environment handle.
An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.
The LOB or BFILE locator being tested.
Returns TRUE if the given LOB or BFILE locator is initialized; returns FALSE if it is not.
Tests to see if a given LOB or BFILE locator is initialized.
Internal LOB locators can be initialized by one of these methods:
Selecting a non-NULL LOB into the locator
Pinning an object that contains a non-NULL LOB attribute by OCIObjectPin()
Setting the locator to empty by OCIAttrSet()
See Also:
"LOB Locator Attributes"BFILE locators can be initialized by one of these methods:
Selecting a non-NULL BFILE into the locator
Pinning an object that contains a non-NULL BFILE attribute by OCIObjectPin()
Calling OCILobFileSetName()
The service context handle.
An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.
The LOB to open. The locator can refer to an internal or external LOB.
The mode in which to open the LOB or BFILE. In Oracle8i or later, valid modes for LOBs are OCI_LOB_READONLY and OCI_LOB_READWRITE. Note that OCI_FILE_READONLY exists as input to OCILobFileOpen(). OCI_FILE_READONLY can be used with OCILobOpen() if the input locator is for a BFILE.
It is an error to open the same LOB twice. BFILEs cannot be opened in read/write mode. If a user tries to write to a LOB or BFILE that was opened in read-only mode, an error is returned.
Opening a LOB requires a round-trip to the server for both internal and external LOBs. For internal LOBs, the open triggers other code that relies on the open call. For external LOBs (BFILEs), open requires a round-trip because the actual operating system file on the server side is being opened.
It is not necessary to open a LOB to perform operations on it. When using function-based indexes, extensible indexes or context, and making multiple calls to update or write to the LOB, you should first call OCILobOpen(), then update the LOB as many times as you want, and finally call OCILobClose(). This sequence of operations ensures that the indexes are only updated once at the end of all the write operations instead of once for each write operation.
It is not mandatory that you wrap all LOB operations inside the open and close calls. However, if you open a LOB, then you must close it before you commit your transaction. When an internal LOB is closed, it updates the functional and domain indexes on the LOB column. It is an error to commit the transaction before closing all opened LOBs that were opened by the transaction.
When the error is returned, the LOB is no longer marked as open, but the transaction is successfully committed. Hence, all the changes made to the LOB and non-LOB data in the transaction are committed, but the domain and function-based indexing are not updated. If this happens, rebuild your functional and domain indexes on the LOB column.
If you do not wrap your LOB operations inside the open or close API, then the functional and domain indexes are updated each time you write to the LOB. This can adversely affect performance, so if you have functional or domain indexes, Oracle recommends that you enclose write operations to the LOB within the open or close statements.
See Also:
"Functions for Opening and Closing LOBs"Reads a portion of a LOB or BFILE, as specified by the call, into a buffer. This function must be used for LOBs of size greater than 4 GB. You can also use this function for LOBs smaller than 4 GB.
sword OCILobRead2 ( OCISvcCtx *svchp,
OCIError *errhp,
OCILobLocator *locp,
oraub8 *byte_amtp,
oraub8 *char_amtp,
oraub8 offset,
void *bufp,
oraub8 bufl,
ub1 piece,
void *ctxp,
OCICallbackLobRead2 (cbfp)
( void *ctxp,
const void *bufp,
oraub8 lenp,
ub1 piecep
void **changed_bufpp,
oraub8 *changed_lenp
)
ub2 csid,
ub1 csfrm );
The service context handle.
An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.
A LOB or BFILE locator that uniquely references the LOB or BFILE. This locator must have been a locator that was obtained from the server specified by svchp.
IN - The number of bytes to read from the database. Used for BLOB and BFILE always. For CLOB and NCLOB, it is used only when char_amtp is zero.
OUT - The number of bytes read into the user buffer.
IN - The maximum number of characters to read into the user buffer. Ignored for BLOB and BFILE.
OUT - The number of characters read into the user buffer. Undefined for BLOB and BFILE.
On input, this is the absolute offset from the beginning of the LOB value. For character LOBs (CLOBs, NCLOBs), it is the number of characters from the beginning of the LOB; for binary LOBs or BFILEs, it is the number of bytes. The first position is 1.
If you use streaming (by polling or a callback), specify the offset in the first call; in subsequent polling calls, the offset parameter is ignored. When you use a callback, there is no offset parameter.
The pointer to a buffer into which the piece is read. The length of the allocated memory is assumed to be bufl.
The length of the buffer in octets. This value differs from the amtp value for CLOBs and for NCLOBs (csfrm=SQLCS_NCHAR) when the amtp parameter is specified in terms of characters, and the bufl parameter is specified in terms of bytes.
OCI_ONE_PIECE - The call never assumes polling. If the amount indicated is more than the buffer length, then the buffer is filled as much as possible.
For polling, pass OCI_FIRST_PIECE the first time and OCI_NEXT_PIECE in subsequent calls. OCI_FIRST_PIECE should be passed while using the callback.
The context pointer for the callback function. Can be NULL.
A callback that can be registered to be called for each piece. If this is NULL, then OCI_NEED_DATA is returned for each piece.
The callback function must return OCI_CONTINUE for the read to continue. If any other error code is returned, the LOB read is terminated.
The context for the callback function. Can be NULL.
A buffer pointer for the piece.
The length in bytes of the current piece in bufp.
Which piece: OCI_FIRST_PIECE, OCI_NEXT_PIECE, or OCI_LAST_PIECE.
The callback function can put the address of a new buffer if it prefers to use a new buffer for the next piece to read. The default old buffer bufp is used if this parameter is set to NULL.
Length of the new buffer, if provided.
The character set ID of the buffer data. If this value is 0, then csid is set to the client's NLS_LANG or NLS_CHAR value, depending on the value of csfrm. It is never assumed to be the server character set, unless the server and client have the same settings.
The character set form of the buffer data. The csfrm parameter must be consistent with the type of the LOB.
The csfrm parameter has two possible nonzero values:
The default value is SQLCS_IMPLICIT. If csfrm is not specified, the default is assumed.
Reads a portion of a LOB or BFILE as specified by the call into a buffer. It is an error to try to read from a NULL LOB or BFILE.
Note:
When you read or write LOBs, specify a character set form (csfrm) that matches the form of the locator itself.For BFILEs, the operating system file must exist on the server, and it must have been opened by OCILobFileOpen() or OCILobOpen() using the input locator. Oracle Database must have permission to read the operating system file, and the user must have read permission on the directory object.
When you use the polling mode for OCILobRead2(), the first call must specify values for offset and amtp, but on subsequent polling calls to OCILobRead2(), you need not specify these values.
If the LOB is a BLOB, the csid and csfrm parameters are ignored.
Note:
To terminate anOCILobRead2() operation and free the statement handle, use the OCIBreak() call.The following points apply to reading LOB data in streaming mode:
When you use polling mode, be sure to specify the char_amtp and byte_amtp and offset parameters only in the first call to OCILobRead2(). On subsequent polling calls these parameters are ignored. If both byte_amtp and char_amtp are set to point to zero and OCI_FIRST_PIECE is passed, then polling mode is assumed and data is read till the end of the LOB. On output, byte_amtp gives the number of bytes read in the current piece. For CLOBs and NCLOBs, char_amtp gives the number of characters read in the current piece.
When you use callbacks, the len parameter, which is input to the callback, indicates how many bytes are filled in the buffer. Check the len parameter during your callback processing, because the entire buffer cannot be filled with data.
When you use polling, look at the byte_amtp parameter to see how much the buffer is filled for the current piece. For CLOBs and NCLOBs, char_amtp returns the number of characters read in the buffer as well.
To read data in UTF-16 format, set the csid parameter to OCI_UTF16ID. If the csid parameter is set, it overrides the NLS_LANG environment variable.
See Also:
"PL/SQL REF CURSORs and Nested Tables in OCI" for additional information about Unicode format
Oracle Database SecureFiles and Large Objects Developer's Guide for a description of BFILEs
The demonstration programs included with your Oracle Database installation for a code sample showing the use of LOB reads and writes.
"Runtime Data Allocation and Piecewise Operations in OCI" for general information about piecewise OCI operations
Sets a content type string for the data in the SecureFile to something that can be used by an application.
sword OCILobSetContentType ( OCIEnv *envhp,
OCISvcCtx *svchp,
OCIError *errhp,
OCILobLocator *lobp,
const oratext *contenttypep,
ub4 contenttypelen,
ub4 mode);
The environment handle.
The service context handle.
An error handle that can be passed to OCIErrorGet() for diagnostic information when there is an error.
A LOB locator that uniquely references a LOB.
The contenttype to be set for the given LOB.
The size of contenttype in bytes. The size must be less than or equal to OCI_LOB_CONTENTTYPE_MAXSIZE bytes.
For future use. Pass zero now.
This function only works on SecureFiles. If lobp is not a SecureFile, then the error SECUREFILE_WRONGTYPE is returned. If lobp is buffered, a temporary LOB, or an abstract LOB, then the error SECUREFILE_BADLOB is returned.
The maximum possible size of the ContentType string is defined as:
#define OCI_LOB_CONTENTTYPE_MAXSIZE 128
The ContentType is ASCII (that is, 1-byte/7-bit UTF8).
To clear an existing contenttype set on a SecureFile, invoke OCILobSetContentType() with contenttypep set to (oratext *)0 and contenttypelen set to 0.
sword OCILobSetOptions ( OCISvcCtx *svchp,
OCIError *errhp,
OCILobLocator *locp,
ub4 option_types,
void *optionsp,
ub4 optionslen,
ub4 mode );
The service context handle.
An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.
The LOB locator that uniquely references the LOB. This locator must have been a locator that was obtained from the server specified by svchp.
You can specify multiple option types and values by using the bit-wise inclusive OR ("|"). An error results if you specify an option_types value that is not enabled on the LOB column.
Compression - OCI_LOB_OPT_COMPRESS
Deduplication - OCI_LOB_OPT_DEDUPLICATE
The possible settings are:
OCI_LOB_OPT_COMPRESS_OFF
OCI_LOB_OPT_COMPRESS_ON
OCI_LOB_OPT_DEDUPLICATE_OFF
OCI_LOB_OPT_DEDUPLICATE_ON
The length of the value in optionsp. Note that the only valid length at this time is sizeof(ub4).
Reserved for future use. Pass in 0.
Truncates the LOB value to a shorter length. This function must be used for LOBs of size greater than 4 GB. You can also use this function for LOBs smaller than 4 GB.
The service context handle.
An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.
An internal LOB locator that uniquely references the LOB. This locator must have been a locator that was obtained from the server specified by svchp.
The new length of the LOB value, which must be less than or equal to the current length. For character LOBs, it is the number of characters; for binary LOBs and BFILEs, it is the number of bytes in the LOB.
This function trims the LOB data to a specified shorter length. The function returns an error if newlen is greater than the current LOB length. This function is valid only for internal LOBs. BFILEs are not allowed.
It is not mandatory that you wrap this LOB operation inside the open or close calls. If you did not open the LOB before performing this operation, then the functional and domain indexes on the LOB column are updated during this call. However, if you did open the LOB before performing this operation, then you must close it before you commit your transaction. When an internal LOB is closed, it updates the functional and domain indexes on the LOB column.
If you do not wrap your LOB operations inside the open or close API, then the functional and domain indexes are updated each time you write to the LOB. This can adversely affect performance. If you have functional or domain indexes, Oracle recommends that you enclose write operations to the LOB within the open or close statements.
Writes a buffer into a LOB. This function must be used for LOBs of size greater than 4 GB. You can also use this function for LOBs smaller than 4 GB.
sword OCILobWrite2 ( OCISvcCtx *svchp,
OCIError *errhp,
OCILobLocator *locp,
oraub8 *byte_amtp,
oraub8 *char_amtp,
oraub8 offset,
void *bufp,
oraub8 buflen,
ub1 piece,
void *ctxp,
OCICallbackLobWrite2 (cbfp)
(
void *ctxp,
void *bufp,
oraub8 *lenp,
ub1 *piecep
void **changed_bufpp,
oraub8 *changed_lenp
)
ub2 csid,
ub1 csfrm );
The service context handle.
An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.
An internal LOB locator that uniquely references the LOB. This locator must have been a locator that was obtained from the server specified by svchp.
IN - The number of bytes to write to the database. Always used for BLOB. For CLOB and NCLOB it is used only when char_amtp is zero.
OUT - The number of bytes written to the database. In polling mode, it is the length of the piece, in bytes, just written.
IN - The maximum number of characters to write to the database. Ignored for BLOB.
OUT - The number of characters written to the database. Undefined for BLOB. In polling mode, it is the length of the piece, in characters, just written.
On input, it is the absolute offset from the beginning of the LOB value. For character LOBs, it is the number of characters from the beginning of the LOB; for binary LOBs, it is the number of bytes. The first position is 1.
If you use streaming (by polling or a callback), specify the offset in the first call; in subsequent polling calls, the offset parameter is ignored. When you use a callback, there is no offset parameter.
The pointer to a buffer from which the piece is written. The length of the data in the buffer is assumed to be the value passed in buflen. Even if the data is being written in pieces using the polling method, bufp must contain the first piece of the LOB when this call is invoked. If a callback is provided, bufp must not be used to provide data or an error results.
The length, in bytes, of the data in the buffer. This value differs from the char_amtp value for CLOBs and NCLOBs when the amount is specified in terms of characters using the char_amtp parameter, and the buflen parameter is specified in terms of bytes.
Note:
This parameter assumes an 8-bit byte. If your operating system uses a longer byte, you must adjust the value ofbuflen accordingly.Which piece of the buffer is being written. The default value for this parameter is OCI_ONE_PIECE, indicating that the buffer is written in a single piece.
The following other values are also possible for piecewise or callback mode: OCI_FIRST_PIECE, OCI_NEXT_PIECE, and OCI_LAST_PIECE.
The context for the callback function. Can be NULL.
A callback that can be registered to be called for each piece in a piecewise write. If this is NULL, the standard polling method is used.
The callback function must return OCI_CONTINUE for the write to continue. If any other error code is returned, the LOB write is terminated. The callback takes the following parameters:
The context for the callback function. Can be NULL.
A buffer pointer for the piece. This is the same as the bufp passed as an input to the OCILobWrite() routine.
The length (in bytes) of the data in the buffer (IN), and the length (in bytes) of the current piece in bufp (OUT).
Which piece: OCI_NEXT_PIECE or OCI_LAST_PIECE.
The callback function can put the address of a new buffer if it prefers to use a new buffer for next piece to read. The default old buffer bufp is used if this parameter is set to NULL.
Length of the new buffer, if provided.
The character set ID of the data in the buffer. If this value is 0, then csid is set to the client's NLS_LANG or NLS_CHAR value, depending on the value of csfrm.
The character set form of the buffer data. The csfrm parameter must be consistent with the type of the LOB.
The csfrm parameter has two possible nonzero values:
The default value is SQLCS_IMPLICIT.
Writes a buffer into an internal LOB as specified. If LOB data exists, it is overwritten with the data stored in the buffer. The buffer can be written to the LOB in a single piece with this call, or it can be provided piecewise using callbacks or a standard polling method.
Note:
When you read or write LOBs, specify a character set form (csfrm) that matches the form of the locator itself.When you use the polling mode for OCILobWrite2(), the first call must specify values for offset, byte_amtp, and char_amtp, but on subsequent polling calls to OCILobWrite2(), you need not specify these values.
If the value of the piece parameter is OCI_FIRST_PIECE, data may need to be provided through callbacks or polling.
If a callback function is defined in the cbfp parameter, then this callback function is invoked to get the next piece after a piece is written to the pipe. Each piece is written from bufp. If no callback function is defined, then OCILobWrite2() returns the OCI_NEED_DATA error code. The application must call OCILobWrite2() again to write more pieces of the LOB. In this mode, the buffer pointer and the length can be different in each call if the pieces are of different sizes and from different locations.
A piece value of OCI_LAST_PIECE terminates the piecewise write, regardless of whether the polling or callback method is used.
If the amount of data passed to the database (through either input mechanism) is less than the amount specified by the byte_amtp or the char_amtp parameter, an ORA-22993 error is returned.
This function is valid for internal LOBs only. BFILEs are not allowed, because they are read-only. If the LOB is a BLOB, the csid and csfrm parameters are ignored.
If both byte_amtp and char_amtp are set to point to zero amount, and OCI_FIRST_PIECE is given as input, then polling mode is assumed and data is written until you specify OCI_LAST_PIECE. For CLOBs and NCLOBs, byte_amtp and char_amtp return the data written by each piece in terms of number of bytes and number of characters respectively. For BLOBs, byte_amtp returns the number of bytes written by each piece, whereas char_amtp is undefined on output.
To write data in UTF-16 format, set the csid parameter to OCI_UTF16ID. If the csid parameter is set, it overrides the NLS_LANG environment variable.
It is not mandatory that you wrap this LOB operation inside the open or close calls. If you did not open the LOB before performing this operation, then the functional and domain indexes on the LOB column are updated during this call. However, if you did open the LOB before performing this operation, then you must close it before you commit your transaction. When an internal LOB is closed, it updates the functional and domain indexes on the LOB column.
If you do not wrap your LOB operations inside the open or close API, then the functional and domain indexes are updated each time you write to the LOB. This can adversely affect performance. If you have functional or domain indexes, Oracle recommends that you enclose write operations to the LOB within the open or close statements.
See Also:
"PL/SQL REF CURSORs and Nested Tables in OCI" for additional information about Unicode format
The demonstration programs included with your Oracle Database installation for a code sample showing the use of LOB reads and writes.
"Runtime Data Allocation and Piecewise Operations in OCI" for general information about piecewise OCI operations
Writes data starting at the end of a LOB. This function must be used for LOBs of size greater than 4 GB. You can also use this function for LOBs smaller than 4 GB.
sword OCILobWriteAppend2 ( OCISvcCtx *svchp,
OCIError *errhp,
OCILobLocator *locp,
oraub8 *byte_amtp,
oraub8 *char_amtp,
void *bufp,
oraub8 buflen,
ub1 piece,
void *ctxp,
OCICallbackLobWrite2 (cbfp)
(
void *ctxp,
void *bufp,
oraub8 *lenp,
ub1 *piecep
void **changed_bufpp,
oraub8 *changed_lenp
)
ub2 csid,
ub1 csfrm);
The service context handle.
An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.
An internal LOB locator that uniquely references a LOB.
IN - The number of bytes to write to the database. Used for BLOB. For CLOB and NCLOB it is used only when char_amtp is zero.
OUT - The number of bytes written to the database.
IN - The maximum number of characters to write to the database. Ignored for BLOB.
OUT - The number of characters written to the database. Undefined for BLOB.
The pointer to a buffer from which the piece is written. The length of the data in the buffer is assumed to be the value passed in buflen. Even if the data is being written in pieces, bufp must contain the first piece of the LOB when this call is invoked. If a callback is provided, bufp must not be used to provide data or an error results.
The length, in bytes, of the data in the buffer. Note that this parameter assumes an 8-bit byte. If your operating system uses a longer byte, the value of buflen must be adjusted accordingly.
Which piece of the buffer is being written. The default value for this parameter is OCI_ONE_PIECE, indicating that the buffer is written in a single piece. The following other values are also possible for piecewise or callback mode: OCI_FIRST_PIECE, OCI_NEXT_PIECE, and OCI_LAST_PIECE.
The context for the callback function. Can be NULL.
A callback that can be registered to be called for each piece in a piecewise write. If this is NULL, the standard polling method is used. The callback function must return OCI_CONTINUE for the write to continue. If any other error code is returned, the LOB write is terminated. The callback takes the following parameters:
The context for the callback function. Can be NULL.
A buffer pointer for the piece.
The length (in bytes) of the data in the buffer (IN), and the length (in bytes) of the current piece in bufp (OUT).
Which piece: OCI_NEXT_PIECE or OCI_LAST_PIECE.
The callback function can put the address of a new buffer if it prefers to use a new buffer for next piece to be written. The default old buffer bufp is used if this parameter is set to NULL.
Length of the new buffer, if provided.
The character set ID of the buffer data.
The character set form of the buffer data.
The csfrm parameter has two possible nonzero values:
The default value is SQLCS_IMPLICIT.
The buffer can be written to the LOB in a single piece with this call, or it can be provided piecewise using callbacks or a standard polling method. If the value of the piece parameter is OCI_FIRST_PIECE, data must be provided through callbacks or polling. If a callback function is defined in the cbfp parameter, then this callback function is invoked to get the next piece after a piece is written to the pipe. Each piece is written from bufp. If no callback function is defined, then OCILobWriteAppend2() returns the OCI_NEED_DATA error code.
The application must call OCILobWriteAppend2() again to write more pieces of the LOB. In this mode, the buffer pointer and the length can be different in each call if the pieces are of different sizes and from different locations. A piece value of OCI_LAST_PIECE terminates the piecewise write.
The OCILobWriteAppend2() function is not supported if LOB buffering is enabled.
If the LOB is a BLOB, the csid and csfrm parameters are ignored.
If both byte_amtp and char_amtp are set to point to zero amount and OCI_FIRST_PIECE is given as input, then polling mode is assumed and data is written until you specify OCI_LAST_PIECE. For CLOBs and NCLOBs, byte_amtp and char_amtp return the data written by each piece in terms of number of bytes and number of characters respectively. For BLOBs, byte_amtp returns the number of bytes written by each piece whereas char_amtp is undefined on output.
It is not mandatory that you wrap this LOB operation inside the open or close calls. If you did not open the LOB before performing this operation, then the functional and domain indexes on the LOB column are updated during this call. However, if you did open the LOB before performing this operation, then you must close it before you commit your transaction. When an internal LOB is closed, it updates the functional and domain indexes on the LOB column.
If you do not wrap your LOB operations inside the open or close API, then the functional and domain indexes are updated each time you write to the LOB. This can adversely affect performance. If you have functional or domain indexes, Oracle recommends that you enclose write operations to the LOB within the open or close statements.
See Also:
"Improving LOB Read/Write Performance"