This chapter provides reference information for the Transaction Log API (XLA) described in Chapter 5, "XLA and TimesTen Event Management". It includes the following topics:
This section provides general information about XLA functions.
All of the XLA API functions described in this chapter return a value of type SQLRETURN
, which is defined by ODBC to have one of the following values:
SQL_SUCCESS
SQL_SUCCESS_WITH_INFO
SQL_NO_DATA_FOUND
SQL_ERROR
See "Handling XLA errors" for information on handling XLA errors.
In the function descriptions:
All parameters are input-only unless otherwise indicated.
Output parameters are prefixed with OUT
.
Input/output parameters are prefixed with IN OUT
.
Most routines in this API copy results to application buffers. Those few routines that produce pointers to buffers containing results are guaranteed as valid only until the next call with the same XLA handle.
Exceptions to this rule include the following.
Buffers remain valid across calls to the ttXlaError
function that supplies diagnostic information.
Results returned by ttXlaNextUpdate
remain valid until the next call to ttXlaNextUpdate
.
For ttXlaAcknowledge
, if the application must retain access to the buffers for a longer time, it must copy the information from the buffer returned by XLA to an application-owned buffer.
Character string values in XLA are null-terminated, except for actual column values. Fixed-length CHAR
columns are space-padded to their full length. VARCHAR
columns have an explicit length encoded.
XLA uses the same data structures for both 32-bit and 64-bit platforms. The types SQLUINTEGER
and SQLUBIGINT
are used to refer to 32-bit and 64-bit integers unambiguously. Issues of alignment and padding are addressed by filling the type definition so that each SQLUINTEGER
value is on a four-byte boundary and each SQLUBIGINT
value is on an eight-byte boundary. For a description of storage requirements for other TimesTen data types, see "Understanding rows" in Oracle TimesTen In-Memory Database Operations Guide.
"Access control impact on XLA" introduces the effects of TimesTen access control features on XLA functionality. Any XLA functionality requires the system privilege XLA
.
As described in Chapter 5, "XLA and TimesTen Event Management", TimesTen XLA can be used to detect updates on a database or as a toolkit to build your own replication solution.
This section categorizes the XLA functions based on their use and provides a brief description of each function. It includes the following categories:
The following table lists all the XLA functions used in typical XLA operations, aside from data conversion functions which are listed separately below.
Function | Description |
---|---|
ttXlaAcknowledge |
Acknowledges receipt of one or more transaction update records from the transaction log. |
ttXlaClose |
Closes the XLA handle opened by ttXlaPersistOpen . |
ttXlaConvertCharType |
Converts column data into the connection character set. |
ttXlaDeleteBookmark |
Deletes a transaction log bookmark. |
ttXlaError |
Retrieves error information. |
ttXlaErrorRestart |
Resets error stack information. |
ttXlaGetColumnInfo |
Retrieves information about all the columns in the table. |
ttXlaGetLSN |
Retrieves the log record identifier of the current bookmark for a database. |
ttXlaGetTableInfo |
Retrieves information about a table. |
ttXlaGetVersion |
Retrieves the current version of XLA. |
ttXlaNextUpdate |
Retrieves a batch of updates from TimesTen. |
ttXlaNextUpdateWait |
Retrieves a batch of updates from TimesTen. Waits for a specified time if no updates are available in the transaction log. |
ttXlaPersistOpen |
Initializes a handle to a database to access the transaction log. |
ttXlaSetLSN |
Sets the log record identifier of the current bookmark for a database. |
ttXlaSetVersion |
Sets the XLA version to be used. |
ttXlaTableByName |
Finds the system and user table identifiers for a table given the table owner and name. |
ttXlaTableStatus |
Sets and retrieves XLA status for a table. |
ttXlaTableVersionVerify |
Checks whether the cached table definitions are compatible with the XLA record being processed. |
ttXlaVersionColumnInfo |
Retrieves information about the columns in a table for which a change update record must be processed. |
ttXlaVersionCompare |
Compares two XLA versions. |
See "Writing an XLA event-handler application" for a discussion on how to use most of these functions.
The following table lists data type conversion functions.
Function | Description |
---|---|
ttXlaDateToODBCCType |
Converts a TTXLA_DATE_TT value to an ODBC C value usable by applications. |
ttXlaDecimalToCString |
Converts a TTXLA_DECIMAL_TT value to a character string usable by applications. |
ttXlaNumberToBigInt |
Converts a TTXLA_NUMBER value to a SQLBIGINT C value usable by applications. |
ttXlaNumberToCString |
Converts a TTXLA_NUMBER value to a character string usable by applications. |
ttXlaNumberToDouble |
Converts a TTXLA_NUMBER value to a long floating point number value usable by applications. |
ttXlaNumberToInt |
Converts a TTXLA_NUMBER value to an integer usable by applications. |
ttXlaNumberToSmallInt |
Converts a TTXLA_NUMBER value to a SQLSMALLINT C value usable by applications. |
ttXlaNumberToTinyInt |
Converts a TTXLA_NUMBER value to a SQLCHAR C value usable by applications. |
ttXlaNumberToUInt |
Converts a TTXLA_NUMBER value to an unsigned integer usable by applications. |
ttXlaOraDateToODBCTimeStamp |
Converts a TTXLA_DATE value to an ODBC timestamp usable by applications. |
ttXlaOraTimeStampToODBCTimeStamp |
Converts a TTXLA_TIMESTAMP value to an ODBC timestamp usable by applications. |
ttXlaRowidToCString |
Converts a ROWID value to a character string value usable by applications. |
ttXlaTimeToODBCCType |
Converts a TTXLA_TIME value to an ODBC C value usable by applications. |
ttXlaTimeStampToODBCCType |
Converts a TTXLA_TIMESTAMP_TT value to an ODBC C value usable by applications. |
For more information about XLA data types, see "About XLA data types".
TimesTen replication as described in Oracle TimesTen In-Memory Database Replication Guide is sufficient for most customer needs; however, it is also possible to use XLA functions to replicate updates from one database to another. Implementing your own replication scheme on top of XLA in this way is fairly complicated, but can be considered if TimesTen replication is not feasible for some reason.
The following table lists functions used exclusively for XLA as a replication mechanism. (Reference information for these functions is in a separate section from other XLA functions, "XLA replication function reference".)
Function | Description |
---|---|
ttXlaApply |
Applies the update to the database associated with the XLA handle. |
ttXlaCommit |
Commits a transaction. |
ttXlaGenerateSQL |
Generates a SQL statement that expresses the effect of an update record. |
ttXlaLookup |
Looks for an update record for a table with a specific key value. |
ttXlaRollback |
Rolls back a transaction. |
ttXlaTableCheck |
Verifies that the named table in the table description received from the sending database is compatible with the receiving database. |
See "Using XLA as a replication mechanism" for a discussion on how to use these functions.
This section provides reference information for XLA core functions and XLA data type conversion functions. The functions are listed in alphabetical order.
Note:
Functions used exclusively for XLA as a replication mechanism are documented in a separate section, "XLA replication function reference".This function is used to acknowledge that one or more records have been read from the transaction log by the ttXlaNextUpdate
or ttXlaNextUpdateWait
function.
After you make this call, the bookmark is reset so that you cannot reread any of the previously returned records. Call ttXlaAcknowledge
only when messages have been completely processed.
Notes:
The bookmark is only reset for the specified handle. Other handles in the system may still be able to access those earlier transactions.
The bookmark is reset even if there are no relevant update records to acknowledge.
Note that ttXlaAcknowledge
is an expensive operation that should be used only as necessary. Calling ttXlaAcknowledge
more than once per reading of the transaction log file does not reduce the volume of the transaction log since XLA only purges transaction logs a file at a time. To detect when a new transaction log file is generated, you can find out which log file a bookmark is in by examining the purgeLSN
(represented by the PURGELSNHIGH
and PURGELSNLOW
values) for the bookmark in the system table SYS.TRANSACTION_LOG_API
. You can then call ttXlaAcknowledge
to purge the old transaction log files. (Note that you must have ADMIN
or SELECT ANY TABLE
privilege to view this table.)
The second purpose of ttXlaAcknowledge
is to ensure that the XLA application does not see the acknowledged records if it were to connect to a previously used bookmark by calling the ttXlaPersistOpen
function with the XLAREUSE
option. If you intend to reuse a bookmark, call ttXlaAcknowledge
to reset the bookmark position to the current record before calling ttXlaClose
.
See "Retrieving update records from the transaction log" for a discussion about using this function.
Returns SQL_SUCCESS
if call is successful. Otherwise, use ttXlaError
to report the error.
Closes an XLA handle that was opened by ttXlaPersistOpen
. See "Terminating an XLA application" for a discussion about using this function.
Returns SQL_SUCCESS
if call is successful. Otherwise, use ttXlaError
to report the error.
To close the XLA handle opened in the previous example, use the following call:
rc = ttXlaClose(xlahandle);
Converts the column data indicated by the colinfo
and tup
parameters into the connection character set associated with the transaction log handle and places the result in a buffer.
SQLRETURN ttXlaConvertCharType (ttXlaHandle_h handle, ttXlaColDesc_t* colinfo, void* tup, void* buf, size_t buflen)
Parameter | Type | Description |
---|---|---|
handle |
ttXlaHandle_h |
Transaction log handle for the database |
colinfo |
ttXlaColDesc_t* |
Pointer to the buffer that holds the column descriptions |
tup |
void* |
Data to be converted |
buf |
void* |
Location where the converted data is placed |
buflen |
size_t |
Size of the buffer where the converted data is placed |
Returns SQL_SUCCESS
if call is successful. Otherwise, use ttXlaError
to report the error.
Converts a TTXLA_DATE_TT
value to an ODBC C value usable by applications. See "Converting complex data types" for a discussion about using this function.
Call this function only on a column of data type TTXLA_DATE_TT
. The data type can be obtained from the ttXlaColDesc_t
structure returned by the ttXlaGetColumnInfo
function.
Parameter | Type | Description |
---|---|---|
fromData |
void* |
Pointer to the date value returned from the transaction log |
returnData |
DATE_STRUCT* |
Pointer to storage allocated to hold the converted date |
Returns SQL_SUCCESS
if call is successful. Otherwise, use ttXlaError
to report the error.
Converts a TTXLA_DECIMAL_TT
value to a string usable by applications. The scale and precision values can be obtained from the ttXlaColDesc_t
structure returned by the ttXlaGetColumnInfo
function. The scale
parameter specifies the maximum number of digits after the decimal point. If the decimal value is larger than 1, the precision
parameter should specify the maximum number of digits before and after the decimal point. If the decimal value is less than 1, precision
equals scale
.
Call this function only for a column of type TTXLA_DECIMAL_TT
. The data type can be obtained from the ttXlaColDesc_t
structure returned by the ttXlaGetColumnInfo
function.
See "Converting complex data types" for a discussion about using this function.
SQLRETURN ttXlaDecimalToCString(void* fromData, out char* returnData, SQLSMALLINT precision, SQLSMALLINT scale)
Parameter | Type | Description |
---|---|---|
fromData |
void* |
Pointer to the decimal value returned from the transaction log |
returnData |
char* |
Pointer to storage allocated to hold the converted string |
precision |
SQLSMALLINT |
If fromData is greater than 1, the maximum number of digits before and after the decimal point
If |
scale |
SQLSMALLINT |
Maximum number of digits after the decimal point |
Returns SQL_SUCCESS
if call is successful. Otherwise, use ttXlaError
to report the error.
This example assumes you have obtained the offset
, precision
, and scale
values from a ttXlaColDesc_t
structure and used the offset to obtain a decimal value, pColVal
, in a row returned in a transaction log record.
char decimalData[50]; static ttXlaColDesc_t colDesc[255]; rc = ttXlaDecimalToCString(pColVal, (char*)&decimalData, colDesc->precision, colDesc->scale);
Deletes the bookmark associated with the specified transaction log handle. After the bookmark has been deleted, it is no longer accessible and its identifier may be reused for another bookmark. The deleted bookmark is no longer associated with the database handle and the effect is the same as having opened the connection with the XLANONE
option.
If the bookmark is in use, it cannot be deleted until it is no longer in use.
See "Deleting bookmarks" for a discussion about using this function.
Notes:
Do not confuse this with the TimesTen built-in procedure ttXlaBookmarkDelete
, documented in "ttXlaBookmarkDelete" in Oracle TimesTen In-Memory Database Reference.
You cannot delete replicated bookmarks while the replication agent is running.
Returns SQL_SUCCESS
if call is successful. Otherwise, use ttXlaError
to report the error.
Reports details of any errors encountered from the previous call on the given transaction log handle. Multiple errors may be returned through subsequent calls to ttXlaError
. The error stack is cleared following each call to a function other than ttXlaError
itself and ttXlaErrorRestart
.
See "Handling XLA errors" for a discussion about using this function.
SQLRETURN ttXlaError(ttXlaHandle_h handle, out SQLINTEGER* errCode, out char* errMessage, SQLINTEGER maxLen, out SQLINTEGER* retLen)
Parameter | Type | Description |
---|---|---|
handle |
ttXlaHandle_h |
Transaction log handle for the database |
errCode |
SQLINTEGER* |
Code of the error message to be copied into the errMessage buffer |
errMessage |
char* |
Buffer to hold the error text |
maxLen |
SQLINTEGER |
Maximum length of the errMessage buffer |
retLen |
SQLINTEGER* |
Actual size of the error message |
Returns SQL_SUCCESS
if error information is returned, or SQL_NO_DATA_FOUND
if no more errors are found in the error stack. If the errMessage
buffer is not large enough, ttXlaError
returns SQL_SUCCESS_WITH_INFO
.
There can be multiple errors on the error stack. This example shows how to read them all.
char message[100]; SQLINTEGER code; for (;;) { rc = ttXlaError(xlahandle, &code, message, sizeof (message), &retLen); if (rc == SQL_NO_DATA_FOUND) break; if (rc == SQL_ERROR) { printf("Error in fetching error message\n"); break; } else { printf("Error code %d: %s\n", code, message); } }
If you use multiple threads to access a TimesTen transaction log over a single XLA connection, TimesTen creates a latch to control concurrent access. If for some reason the latch cannot be acquired by a thread, the XLA function returns SQL_INVALID_HANDLE
.
Resets the error stack so that an application can reread the errors. See "Handling XLA errors" for a discussion about using this function.
Returns SQL_SUCCESS
if call is successful. Otherwise, use ttXlaError
to report the error.
Retrieves information about all the columns in the table. Normally, the output parameter for number of columns returned, nreturned
, is set to the number of columns returned in colinfo
. The systemTableID
or userTableID
parameter describes the desired table. This call is serialized with respect to changes in the table definition.
See "Obtaining column descriptions" for a discussion about using this function.
SQLRETURN ttXlaGetColumnInfo(ttXlaHandle_h handle, SQLUBIGINT systemTableID, SQLUBIGINT userTableID, out ttXlaColDesc_t* colinfo, SQLINTEGER maxcols, out SQLINTEGER* nreturned)
Parameter | Type | Description |
---|---|---|
handle |
ttXlaHandle_h |
Transaction log handle for the database |
systemTableID |
SQLUBIGINT |
System ID of table |
userTableID |
SQLUBIGINT |
User ID of table |
colinfo |
ttXlaColDesc_t* |
Pointer to the buffer large enough to hold a separate description for maxcols columns |
maxcols |
SQLINTEGER |
Maximum number of columns that can be stored in the colInfo buffer
If the table contains more than |
nreturned |
SQLINTEGER* |
Number of columns returned |
Returns SQL_SUCCESS
if call is successful. Otherwise, use ttXlaError
to report the error.
For this example, assume the following definitions:
ttXlaColDesc_t colinfo[20]; SQLUBIGINT systemTableID, userTableID; SQLINTEGER ncols;
To get the description of up to 20 columns using the system table identifier, issue the following call.
rc = ttXlaGetColumnInfo(xlahandle, systemTableID, 0, colinfo, 20, &ncols);
Likewise, the user table identifier can be used:
rc = ttXlaGetColumnInfo(xlahandle, 0, userTableID, colinfo, 20, &ncols);
See "ttXlaColDesc_t" for details and an example on how to access the column data in a returned row.
Returns the Current Read log record identifier for the connection specified by the transaction log handle. See "How bookmarks work" for a discussion about using this function.
Parameter | Type | Description |
---|---|---|
handle |
ttXlaHandle_h |
Transaction log handle for the database |
LSN |
tt_XlaLsn_t* |
Current Read log record identifier for the handle |
Note:
Be aware thattt_XlaLsn_t
, particularly the logFile
and logOffset
fields, is used differently than in earlier releases, referring to log record identifiers rather than sequentially increasing LSNs. See the note in "tt_XlaLsn_t".Returns SQL_SUCCESS
if call is successful. Otherwise, use ttXlaError
to report the error.
This example returns the Current Read log record identifier, CurLSN
.
tt_XlaLsn_t CurLSN; rc = ttXlaGetLSN(xlahandle, &CurLSN);
Retrieves information about the rows in the table (refer to the description of the ttXlaTblDesc_t
data type.) If the userTableID
parameter is nonzero, then it is used to locate the desired table. Otherwise, the systemTableID
value is used to locate the table. If both are zero, an error is returned. The description is stored in the output parameter tblinfo
. This call is serialized with respect to changes in the table definition.
SQLRETURN ttXlaGetTableInfo(ttXlaHandle_h handle, SQLUBIGINT systemTableID, SQLUBIGINT userTableID, out ttXlaTblDesc_t* tblinfo)
Parameter | Type | Description |
---|---|---|
handle |
ttXlaHandle_h |
Transaction log handle for the database |
systemTableID |
SQLUBIGINT |
System table ID |
userTableID |
SQLUBIGINT |
User table ID |
tblinfo |
ttXlaTblDesc_t* |
Row information |
Returns SQL_SUCCESS
if call is successful. Otherwise, use ttXlaError
to report the error.
For this example, assume the following definitions:
ttXlaTblDesc_t tabinfo; SQLUBIGINT systemTableID, userTableID;
To get table information using a system identifier, find the system table identifier using ttXlaTableByName
or other means and issue the following call:
rc = ttXlaGetTableInfo(xlahandle, systemTableID, 0, &tabinfo);
Alternatively, the table information can be retrieved using a user table identifier:
rc = ttXlaGetTableInfo(xlahandle, 0, userTableID, &tabinfo);
This function is used in combination with ttXlaSetVersion
to ensure XLA applications written for older versions of XLA operate on a new version. The configured version is typically the older version, while the actual version is the newer one.
The function retrieves the currently configured XLA version and stores it into configuredVersion
parameter. The actual version of the underlying XLA is stored in actualVersion
. Due to calls on ttXlaSetVersion
, the results in configuredVersion
may vary from one call to the next, but the results in actualVersion
remain the same.
See "XLA basics" for a discussion about using this function.
SQLRETURN ttXlaGetVersion(ttXlaHandle_h handle, out ttXlaVersion_t* configuredVersion, out ttXlaVersion_t* actualVersion)
Parameter | Type | Description |
---|---|---|
handle |
ttXlaHandle_h |
Transaction log handle for the database |
configuredVersion |
ttXlaVersion_t* |
Configured version of XLA |
actualVersion |
ttXlaVersion_t* |
Actual version of XLA |
Returns SQL_SUCCESS
if call is successful. Otherwise, use ttXlaError
to report the error.
Assume the following directions for this example:
ttXlaVersion_t configured, actual;
To determine the current version configuration, use the following call:
rc = ttXlaGetVersion(xlahandle, &configured, &actual);
This function fetches up to a specified maximum number of update records from the transaction log and returns the records associated with committed transactions to a specified buffer. The actual number of returned records is reported in the nreturned
output parameter. This function requires a bookmark to be present in the database and to be associated with the connection used by the function.
Each call to ttXlaNextUpdate
resets the bookmark to the last record read to enable the next call to ttXlaNextUpdate
to return the next list of records.
See "Retrieving update records from the transaction log" for a discussion about using this function.
SQLRETURN ttXlaNextUpdate(ttXlaHandle_h handle, out ttXlaUpdateDesc_t*** records, SQLINTEGER maxrecords, out SQLINTEGER* nreturned)
Parameter | Type | Description |
---|---|---|
handle |
ttXlaHandle_h |
Transaction log handle for the database |
records |
ttXlaUpdateDesc_t*** |
Buffer to hold the completed transaction records |
maxrecords |
SQLINTEGER |
Maximum number of records to be fetched |
nreturned |
SQLINTEGER* |
Actual number of returned records, where 0 is returned if no update data is available |
Returns SQL_SUCCESS
if call is successful. Otherwise, use ttXlaError
to report the error.
This example retrieves up to 100 records and describes a loop in which each record can be processed:
ttXlaUpdateDesc_t** records; SQLINTEGER nreturned; SQLINTEGER i; rc = ttXlaNextUpdate(xlahandle, &records, 100, &nreturned); /* Check for errors; if none, process the records */ for (i = 0; i < nreturned; i++) { process(records[i]); }
Updates are generated for all data definition statements, regardless of tracking status. Updates are generated for data update operations for all tracked tables associated with the bookmark.
In addition, updates are generated for certain special operations, including assigning application-level identifiers for tables and columns and changing the tracking status of a table.
This is similar to the ttXlaNextUpdate
function, with the addition of a seconds
parameter that specifies the number of seconds to wait if no records are available in the transaction log. The actual number of seconds of wait time can be up to two seconds more than the specified seconds
value.
Also see "Retrieving update records from the transaction log".
SQLRETURN ttXlaNextUpdateWait(ttXlaHandle_h handle, out ttXlaUpdateDesc_t*** records, SQLINTEGER maxrecords, out SQLINTEGER* nreturned, SQLINTEGER seconds)
Parameter | Type | Description |
---|---|---|
handle |
ttXlaHandle_h |
Transaction log handle for the database |
records |
ttXlaUpdateDesc_t*** |
Buffer to hold completed transaction records |
maxrecords |
SQLINTEGER |
Maximum number of records to be fetched
Note: The largest effective value is 1000 records. |
nreturned |
SQLINTEGER* |
Actual number of records returned, where 0 is returned if no update data is available within the seconds wait period |
seconds |
SQLINTEGER |
Number of seconds to wait if the log is empty |
Returns SQL_SUCCESS
if call is successful. Otherwise, use ttXlaError
to report the error.
This example retrieves up to 100 records and waits for up to 60 seconds if there are no records available in the transaction log.
ttXlaUpdateDesc_t** records; SQLINTEGER nreturned; SQLINTEGER i; rc = ttXlaNextUpdateWait(xlahandle, &records, 100, &nreturned, 60); /* Check for errors; if none, process the records */ for (i = 0; i < nreturned; i++) { process(records[i]); }
Converts a TTXLA_NUMBER
value to a SQLBIGINT
value usable by an application.
Call this function only for a column of type TTXLA_NUMBER
. The data type can be obtained from the ttXlaColDesc_t
structure returned by the ttXlaGetColumnInfo
function.
Parameter | Type | Description |
---|---|---|
fromData |
void* |
Pointer to the number value returned from the transaction log |
bint |
SQLBIGINT* |
The SQLBIGINT value converted from the XLA number value |
Returns SQL_SUCCESS
if call is successful. Otherwise, use ttXlaError
to report the error.
Converts a TTXLA_NUMBER
value to a character string usable by an application.
Call this function only for a column of type TTXLA_NUMBER
. The data type can be obtained from the ttXlaColDesc_t
structure returned by the ttXlaGetColumnInfo
function.
SQLRETURN ttXlaNumberToCString(ttXlaHandle_h handle, void* fromData, char* buf, int buflen int* reslen)
Parameter | Type | Description |
---|---|---|
fromData |
void* |
Pointer to the number value returned from the transaction log |
buf |
char* |
Location where the converted data is placed |
buflen |
int |
Size of the buffer where the converted data is placed |
reslen |
int* |
Number of bytes that were written, assuming buflen is large enough (otherwise, the number of bytes that would have been written) |
Returns SQL_SUCCESS
if call is successful. Otherwise, use ttXlaError
to report the error.
Converts a TTXLA_NUMBER
value to a long floating point number value usable by applications.
Call this function only for a column of type TTXLA_NUMBER
. The data type can be obtained from the ttXlaColDesc_t
structure returned by the ttXlaGetColumnInfo
function.
Parameter | Type | Description |
---|---|---|
fromData |
void* |
Pointer to the number value returned from the transaction log |
dbl |
double* |
The long floating point number value converted from the XLA number value |
Returns SQL_SUCCESS
if call is successful. Otherwise, use ttXlaError
to report the error.
Converts a TTXLA_NUMBER
value to a SQLINTEGER
value usable by an application.
Call this function only for a column of type TTXLA_NUMBER
. The data type can be obtained from the ttXlaColDesc_t
structure returned by the ttXlaGetColumnInfo
function.
Parameter | Type | Description |
---|---|---|
fromData |
void* |
Pointer to the number value returned from the transaction log |
ival |
SQLINTEGER* |
The SQLINTEGER value converted from the XLA number value |
Returns SQL_SUCCESS
if call is successful. Otherwise, use ttXlaError
to report the error.
Converts a TTXLA_NUMBER
value to a SQLSMALLINT
value usable by an application.
Call this function only for a column of type TTXLA_NUMBER
. The data type can be obtained from the ttXlaColDesc_t
structure returned by the ttXlaGetColumnInfo
function.
Parameter | Type | Description |
---|---|---|
fromData |
void* |
Pointer to the number value returned from the transaction log |
smint |
SQLSMALLINT* |
The SQLSMALLINT value converted from the XLA number value |
Returns SQL_SUCCESS
if call is successful. Otherwise, use ttXlaError
to report the error.
Converts a TTXLA_NUMBER
value to a tiny integer value usable by an application.
Call this function only for a column of type TTXLA_NUMBER
. The data type can be obtained from the ttXlaColDesc_t
structure returned by the ttXlaGetColumnInfo
function.
Parameter | Type | Description |
---|---|---|
fromData |
void* |
Pointer to the number value returned from the transaction log |
tiny |
SQLCHAR* |
The tiny integer value converted from the XLA number value |
Returns SQL_SUCCESS
if call is successful. Otherwise, use ttXlaError
to report the error.
Converts a TTXLA_NUMBER
value to an unsigned integer value usable by an application.
Call this function only for a column of type TTXLA_NUMBER
. The data type can be obtained from the ttXlaColDesc_t
structure returned by the ttXlaGetColumnInfo
function.
Parameter | Type | Description |
---|---|---|
fromData |
void* |
Pointer to the number value returned from the transaction log |
ival |
SQLUINTEGER* |
The integer value converted from the XLA number value |
Returns SQL_SUCCESS
if call is successful. Otherwise, use ttXlaError
to report the error.
Converts a TTXLA_DATE
value to an ODBC timestamp.
Call this function only for a column of type TTXLA_DATE
. The data type can be obtained from the ttXlaColDesc_t
structure returned by the ttXlaGetColumnInfo
function.
Parameter | Type | Description |
---|---|---|
fromData |
void* |
Pointer to the number value returned from the transaction log |
returnData |
TIMESTAMP_STRUCT* |
ODBC timestamp value converted from the XLA Oracle Database DATE value |
Returns SQL_SUCCESS
if call is successful. Otherwise, use ttXlaError
to report the error.
Converts a TTXLA_TIMESTAMP
value to an ODBC timestamp.
Call this function only for a column of type TTXLA_TIMESTAMP
. The data type can be obtained from the ttXlaColDesc_t
structure returned by the ttXlaGetColumnInfo
function.
Parameter | Type | Description |
---|---|---|
fromData |
void* |
Pointer to the number value returned from the transaction log |
returnData |
TIMESTAMP_STRUCT* |
ODBC timestamp value converted from the XLA Oracle Database TIMESTAMP value |
Returns SQL_SUCCESS
if call is successful. Otherwise, use ttXlaError
to report the error.
Initializes a transaction log handle to a database to enable access to the transaction log. The hdbc
parameter is an ODBC connection handle to a database. Create only one XLA handle for each ODBC connection. After you have created an XLA handle on an ODBC connection, do not issue any other ODBC calls over the ODBC connection until it is closed by ttXlaClose
.
The tag
is a string that identifies the XLA bookmark (see "About XLA bookmarks"). The tag
can identify a new bookmark, either non-replicated or replicated, or one that exists in the system, as specified by the options
parameter. The handle
parameter is initialized by this call and must be provided on each subsequent call to XLA.
Some actions can be done without a bookmark. When performing these types of actions, you can use the XLANONE
option to access the transaction log without a bookmark. Actions that cannot be done without a bookmark are the following:
Multiple applications can concurrently read from the transaction log. See "Initializing XLA and obtaining an XLA handle" for a discussion about using this function.
When this function is successful, XLA sets the autocommit mode to off.
If this function fails but still creates a handle, the handle must be closed to prevent memory leaks.
Note:
Space is allocated by this call. CallttXlaClose
to free space when you are done.SQLRETURN ttXlaPersistOpen(SQLHDBC hdbc, SQLCHAR* tag, SQLUINTEGER options, out ttXlaHandle_h* handle)
Parameter | Type | Description |
---|---|---|
hdbc |
SQLHDBC |
ODBC handle for the database |
tag |
SQLCHAR* |
Identifier for the XLA bookmark
This can be null, in which case |
options |
SQLUINTEGER |
Bookmark options:
|
handle |
ttXlaHandle_h* |
Transaction log handle returned by this call |
Returns SQL_SUCCESS
if call is successful. Otherwise, use ttXlaError
to report the error.
This example opens a transaction log, returns a handle named xlahandle
, and creates a new non-replicated bookmark named mybookmark
:
SQLHDBC hdbc; ttXlaHandle_h xlahandle; rc = ttXlaPersistOpen(hdbc, ( SQLCHAR*)mybookmark, XLACREAT, &xlahandle);
Alternatively, create a new replicated bookmark as follows:
SQLHDBC hdbc; ttXlaHandle_h xlahandle; rc = ttXlaPersistOpen(hdbc, ( SQLCHAR*)mybookmark, XLAREPL, &xlahandle);
Multithreaded applications should create a separate XLA handle for each thread. If multiple threads must use the same XLA handle, use a mutex to serialize thread access to that XLA handle so that only one thread can execute an XLA operation at a time.
Parameter | Type | Description |
---|---|---|
fromData |
void* |
Pointer to the ROWID value returned from the transaction log |
buf |
char* |
Pointer to storage allocated to hold the converted string |
buflen |
int |
Length of the converted string |
Returns SQL_SUCCESS
if call is successful. Otherwise, use ttXlaError
to report the error.
Sets the Current Read log record identifier for the database specified by the transaction handle. The specified LSN
value should be returned from ttXlaGetLSN
. It cannot be a user-created value and cannot be earlier than the current bookmark Initial Read log record identifier.
See "About XLA bookmarks" for a discussion about using this function.
Parameter | Type | Description |
---|---|---|
handle |
ttXlaHandle_h |
Transaction log handle for the database |
LSN |
tt_XlaLsn_t* |
New log record identifier for the handle |
Note:
Be aware thattt_XlaLsn_t
, particularly the logFile
and logOffset
fields, is used differently than in earlier releases, referring to log record identifiers rather than sequentially increasing LSNs. See the note in "tt_XlaLsn_t".Returns SQL_SUCCESS
if call is successful. Otherwise, use ttXlaError
to report the error.
This example sets the Current Read log record identifier to CurLSN
.
tt_XlaLsn_t CurLSN; rc = ttXlaSetLSN(xlahandle, &CurLSN);
Sets the version of XLA to be used by the application. This version must be either the same as the version received from ttXlaGetVersion
or from an earlier version.
See "XLA basics" for a discussion about using this function.
Parameter | Type | Description |
---|---|---|
handle |
ttXlaHandle_h |
Transaction log handle for the database |
version |
ttXlaVersion_t* |
Desired version of XLA |
Returns SQL_SUCCESS
if call is successful. Otherwise, use ttXlaError
to report the error.
To set the configured version to the value specified in requestedVersion
, issue the following call:
rc = ttXlaSetVersion(xlahandle, &requestedVersion);
Finds the system and user table identifiers for a table or materialized view by providing the owner and name of the table or view. See "Specifying which tables to monitor for updates" for a discussion about using this function.
SQLRETURN ttXlaTableByName(ttXlaHandle_h handle, char* owner, char* name, out SQLUBIGINT* sysTableID, out SQLUBIGINT* userTableID)
Parameter | Type | Description |
---|---|---|
handle |
ttXlaHandle_h |
Transaction log handle for the database |
owner |
char* |
Owner for the table or view as a string |
name |
char* |
Name of the table or view |
sysTableID |
SQLUBIGINT* |
System table ID |
userTableID |
SQLUBIGINT* |
User table ID |
Returns SQL_SUCCESS
if call is successful. Otherwise, use ttXlaError
to report the error.
To get the system and user table IDs associated with the table PURCHASING.INVOICES
, use the following call:
SQLUBIGINT sysTableID; SQLUBIGINT userTableID; rc = ttXlaTableByName(xlahandle, "PURCHASING", "INVOICES", &sysTableID, &userTableID);
Returns the update status for a table. Identify the table by specifying either a user ID (userTableID
) or a system ID (systemTableID
). If userTableID
is nonzero, it is used to locate the table. Otherwise systemTableID
is used. If both are zero, an error is returned.
Specifying a value for newstatus
sets the update status to *newstatus
. A nonzero status means the table specified by systemTableID
is available through XLA. Zero means the table is not tracked. Changes to table update status are effective immediately.
Updates to a table are tracked only if update tracking was enabled for the table at the time the update was performed. This call is serialized with respect to updates to the underlying table. Therefore, transactions that update the table run either completely before or completely after the change to table status.
To use ttXlaTableStatus
, the user must be connected to a bookmark. The function reports inserts, updates, and deletes only to the bookmark that has subscribed to the table. It reports DDL events to all bookmarks. DDL events include CREATAB
, DROPTAB
, CREAIND
, DROPIND
, CREATVIEW
, DROPVIEW
, CREATSEQ
, DROPSEQ
, CREATSYN
, DROPSYN
, ADDCOLS
, DRPCOLS
, TRUNCATE
, SETTBL1
, and SETCOL1
transactions. See "ttXlaUpdateDesc_t" for information about these event types.
See "Specifying which tables to monitor for updates" for a discussion about using this function.
Note:
DML updates to a table being tracked through XLA do not preventttXlaTableStatus
from running. However, DDL updates to the table being tracked, which take a lock on SYS.TABLES
, do delay ttXlaTableStatus
from running in serializable isolation against SYS.TABLES
.SQLRETURN ttXlaTableStatus(ttXlaHandle_h handle, SQLUBIGINT systemTableID, SQLUBIGINT userTableID, out SQLINTEGER* oldstatus, SQLINTEGER* newstatus)
Parameter | Type | Description |
---|---|---|
handle |
ttXlaHandle_h |
Transaction log handle for the database |
systemTableID |
SQLUBIGINT |
System ID of table |
userTableID |
SQLUBIGINT |
User ID of table |
oldstatus |
SQLINTEGER* |
XLA old status:
|
newstatus |
SQLINTEGER* |
XLA new status:
|
Returns SQL_SUCCESS
if call is successful. Otherwise, use ttXlaError
to report the error.
The following examples assume that the system or user table identifiers are found using ttXlaTableByName
or some other means.
Assume these declarations for the example:
SQLUBIGINT systemTableID; SQLUBIGINT userTableID; SQLINTEGER currentStatus, requestedStatus;
To find the status of a table given its system table identifier, use the following call:
/* Get system table identifier into systemTableID, then ... */ rc = ttXlaTableStatus(xlahandle, systemTableID, 0, ¤tStatus, NULL);
The currentStatus
value is nonzero if update tracking for the table is enabled, or zero otherwise.
To enable update tracking for a table given a system table identifier, set the requested status to 1 as follows:
requestedStatus = 1; rc = ttXlaTableStatus(xlahandle, systemTableID, 0, NULL, &requestedStatus);
You can set a new update tracking status and retrieve the current status in a single call, as in the following example:
requestedStatus = 1; rc = ttXlaTableStatus(xlahandle, systemTableID, 0, ¤tStatus, &requestedStatus);
The above call enables update tracking for a table by system table identifier and retrieves the prior update tracking status in the variable currentStatus
.
All of these examples can be done using user table identifiers as well. To retrieve the update tracking status of a table through its user table identifier, use the following call:
/* Get system table identifier into userTableID, then ... */ rc = ttXlaTableStatus(xlahandle, 0, userTableID, ¤tStatus, NULL);
Verifies that the cached table definitions are compatible with the XLA record being processed. Table definitions change only when the ALTER TABLE
statement is used to add or remove columns.
You can monitor the XLA stream for XLA records of transaction type ADDCOLS
and DRPCOLS
to avoid the overhead of using this function. When an XLA record of transaction type ADDCOLS
or DROPCOLS
is encountered, refresh the table and column definitions. See "Inspecting record headers and locating row addresses" for information about monitoring XLA records for transaction type.
SQLRETURN ttXlaTableVersionVerify(ttXlaHandle_h handle ttXlaTblVerDesc_t* table, ttXlaUpdateDesc_t* record out SQLINTEGER* compat)
Parameter | Type | Description |
---|---|---|
handle |
ttXlaHandle_h |
Transaction log handle for the database |
table |
ttXlaTblVerDesc_t* |
A cached table description |
record |
ttXlaUpdateDesc_t* |
XLA record to be processed |
compat |
SQLINTEGER* |
Compatibility information:
|
Returns SQL_SUCCESS
if cached table definition is compatible with the XLA record being processed. Otherwise, use ttXlaError
to report the error.
This example checks the compatibility of a table.
SQLINTEGER compat; ttXlaTbVerDesc_t table; ttXlaUpdateDesc_t* record; /* * Get the desired table definitions into the variable "table" */ rc = ttXlaTableVersionVerify(xlahandle, &table, record, &compat); if (compat) { /* * Compatible */ } else { /* * Not compatible or some other error occurred * If not compatible, issue a call to ttXlaVersionTableInfo and * ttXlaVersionColumnInfo to get the new definition. */ }
Converts a TTXLA_TIME
value to an ODBC C value usable by applications. See "Converting complex data types" for a discussion about using this function.
Call this function only for a column of type TTXLA_TIME
. The data type can be obtained from the ttXlaColDesc_t
structure returned by the ttXlaGetColumnInfo
function.
Parameter | Type | Description |
---|---|---|
fromData |
void* |
Pointer to the time value returned from the transaction log |
returnData |
TIME_STRUCT* |
Pointer to storage allocated to hold the converted time |
Returns SQL_SUCCESS
if call is successful. Otherwise, use ttXlaError
to report the error.
This example assumes you have used the offset
value returned in a ttXlaColDesc_t
structure to obtain a time value, pColVal
, from a row returned in a transaction log record.
TIME_STRUCT time; rc = ttXlaTimeToODBCCType(pColVal, &time);
Converts a TTXLA_TIMSTAMP_TT
value to an ODBC C value usable by applications. See "Converting complex data types" for a discussion about using this function.
Call this function only for a column of type TTXLA_TIMSTAMP_TT
. The data type can be obtained from the ttXlaColDesc_t
structure returned by the ttXlaGetColumnInfo
function.
Parameter | Type | Description |
---|---|---|
fromData |
void* |
Pointer to the timestamp value returned from the transaction log |
returnData |
TIMESTAMP_STRUCT* |
Pointer to storage allocated to hold the converted timestamp |
Returns SQL_SUCCESS
if call is successful. Otherwise, use ttXlaError
to report the error.
This example assumes you have used the offset
value returned in a ttXlaColDesc_t
structure to obtain a timestamp value, pColVal
, from a row returned in a transaction log record.
TIMESTAMP_STRUCT timestamp; rc = ttXlaTimeStampToODBCCType(pColVal, ×tamp);
Retrieves information about the columns in a table for which a change update XLA record must be processed.
SQLRETURN ttXlaVersionColumnInfo(ttXlaHandle_h handle, ttXlaUpdateDesc_t* record, out ttXlaColDesc_t* colinfo, SQLINTEGER maxcols, out SQLINTEGER* nreturned)
Parameter | Type | Description |
---|---|---|
handle |
ttXlaHandle_h |
Transaction log handle for the database |
record |
ttXlaUpdateDesc_t* |
XLA record to be processed |
colinfo |
ttXlaColDesc_t* |
A pointer to the buffer large enough to hold a description for maxcols columns |
maxcols |
SQLINTEGER |
Maximum number of columns the table can have
Note: If the table contains more than |
nreturned |
SQLINTEGER* |
Number of columns returned |
Returns SQL_SUCCESS
if call is successful. Otherwise, use ttXlaError
to report the error.
SQLRETURN ttXlaVersionCompare(ttXlaHandle_h handle, ttXlaVersion_t* version1, ttXlaVersion_t* version2, out SQLINTEGER* comparison)
Parameter | Type | Description |
---|---|---|
handle |
ttXlaHandle_h |
Transaction log handle for the database |
version1 |
ttXlaVersion_t* |
Version of XLA to compare with version2 |
version2 |
ttXlaVersion_t* |
Version of XLA to compare with version1 |
comparison |
SQLINTEGER* |
Comparison result:
|
Returns SQL_SUCCESS
if call is successful. Otherwise, use ttXlaError
to report the error.
To compare the configured
version against the actual
version of XLA, issue the following call:
ttXlaVersion_t configured, actual; SQLINTEGER comparision; rc = ttXlaGetVersion (xlahandle, &configured, &actual); rc = ttXlaVersionCompare (xlahandle, &configured, &actual, &comparison);
When connecting two systems with XLA-based replication, use the following protocol:
At the primary site, retrieve the XLA version using ttXlaGetVersion
. Send this version information to the standby site.
At the standby site, retrieve the XLA version using ttXlaGetVersion
. Use ttXlaVersionCompare
to determine which version is earlier. The earlier version number must be used to ensure proper operation between the two sites. Use ttXlaSetVersion
to specify the version of the interface to use at the standby site. Send the earlier version number back to the primary site.
When the chosen version is received at the primary site, use ttXlaSetVersion
to specify the version of XLA to use.
Retrieves the table definition for the change update record that must be processed. The table description is stored in the tableinfo
output parameter.
SQLRETURN ttXlaVersionTableInfo(ttXlaHandle_h handle, ttXlaUpdateDesc_t* record, out ttXlaTblVerDesc_t* tblinfo)
Parameter | Type | Description |
---|---|---|
handle |
ttXlaHandle_h |
Transaction log handle for the database |
record |
ttXlaUpdateDesc_t* |
XLA record to be processed |
tableinfo |
ttXlaTblVerDesc_t* |
Information about table definition |
Returns SQL_SUCCESS
if call is successful. Otherwise, use ttXlaError
to report the error.
TimesTen replication as described in Oracle TimesTen In-Memory Database Replication Guide is sufficient for most customer needs; however, it is also possible to use XLA functions to replicate updates from one database to another. Implementing your own replication scheme on top of XLA in this way is fairly complicated, but can be considered if TimesTen replication is not feasible for some reason.
This section documents the functions that are exclusive to using XLA as a replication mechanism. Functions are listed in alphabetical order.
This function is part of XLA replication functionality and is not appropriate for use in a typical XLA application.
Applies an update to the database associated with the transaction log handle. The return value indicates whether the update was successful. The return also shows if the update encountered a persistent problem. (To see whether the update encountered a transient problem such as a deadlock or timeout, you must call ttXlaError
and check the error code.)
If the ttXlaUpdateDesc_t
record is a transaction commit, the underlying database transaction is committed. No other transaction commits are performed by ttXlaApply
. If the parameter test
is true, the "old values" in the update description are compared against the current contents of the database for record updates and deletions. If the old value in the update description does not match the corresponding row in the database, this function rejects the update and returns an sb_ErrXlaTupleMismatch
error.
See "Using XLA as a replication mechanism" for a discussion about using this function.
Note:
ttXlaApply
cannot be used if the table definition was updated since it was originally written to the transaction log. Unique key and foreign key constraints are checked at the row level rather than at the statement level.ADMIN
Additional privileges may be required on the target database for the ttXlaApply
operation. For example, to apply a CREATETAB
(create table) record to the target database, you must have CREATE TABLE
or CREATE ANY TABLE
privilege, as appropriate.
Parameter | Type | Description |
---|---|---|
handle |
ttXlaHandle_h |
Transaction log handle for the database |
record |
ttXlaUpdateDesc_t* |
Transaction to generate SQL statement |
test |
SQLINTEGER |
Test for old values:
|
Returns SQL_SUCCESS
if call is successful. Otherwise, use ttXlaError
to report the error.
If test
is 1 and ttXlaApply
detects an update conflict, an sb_ErrXlaTupleMismatch
error is returned.
This example applies an update to a database without testing for the previous value of the existing record:
ttXlaUpdateDesc_t record; rc = ttXlaApply(xlahandle, &record, 0);
When calling ttXlaApply
, it is possible for the update to timeout or deadlock with concurrent transactions. In such cases, it is the application's responsibility to roll the transaction back and reapply the updates.
This function is part of XLA replication functionality and is not appropriate for use in a typical XLA application.
Commits the current transaction being applied on the transaction log handle. This routine commits the transaction regardless of whether the transaction has completed. You can call this routine to respond to transient errors (timeout or deadlock) reported by ttXlaApply
, which applies the current transaction if it does not encounter an error.
See "Handling timeout and deadlock errors" for a discussion about using this function.
Returns SQL_SUCCESS
if call is successful. Otherwise, use ttXlaError
to report the error.
This function is part of XLA replication functionality and is not appropriate for use in a typical XLA application.
Note:
This function does not currently work with LOB locators.Generates a SQL DML or DDL statement that expresses the effect of the update record. The generated statement is not applied to any database. Instead, the statement is returned in the given buffer, whose maximum size is specified by the maxLen
parameter. The actual size of the buffer is returned in actualLen
. For update and delete records, ttXlaGenerateSQL
requires a primary key or a unique index on a non-nullable column to generate the correct SQL.
The generated SQL statement is encoded in the connection character set that is associated with the ODBC connection of the XLA handle.
SQLRETURN ttXlaGenerateSQL(ttXlaHandle_h handle, ttXlaUpdateDesc_t* record, out char* buffer, SQLINTEGER maxLen, out SQLINTEGER* actualLen)
Parameter | Type | Description |
---|---|---|
handle |
ttXlaHandle_h |
Transaction log handle for the database |
record |
ttXlaUpdateDesc_t* |
Record to be translated into SQL |
buffer |
char* |
Location of the translated SQL statement |
maxLen |
SQLINTEGER |
Maximum length of the buffer, in bytes |
actualLen |
SQLINTEGER* |
Actual length of the buffer, in bytes |
Returns SQL_SUCCESS
if call is successful. Otherwise, use ttXlaError
to report the error.
This example generates the text of a SQL statement that is equivalent to the UPDATE
expressed by an update record:
ttXlaUpdateDesc_t record; char buffer[200]; /* * Get the desired update record into the varable record. */ SQLINTEGER actualLength; rc = ttXlaGenerateSQL(xlahandle, &record, buffer, 200, &actualLength);
The ttXlaGenerateSQL
function cannot generate SQL statements for update records associated with a table that has been dropped or altered since the record was generated.
This function is part of XLA replication functionality and is not appropriate for use in a typical XLA application.
This function looks for a record in the given table with key values according to the keys
parameter. The formats of the keys
and result
records are the same as for ordinary rows. This function requires a primary key on the underlying table.
SQLRETURN ttXlaLookup(ttXlaHandle_h handle, ttXlaTableDesc_t* table, void* keys, out void* result, SQLINTEGER maxsize, out SQLINTEGER* retsize)
Parameter | Type | Description |
---|---|---|
handle |
ttXlaHandle_h |
Transaction log handle for the database |
table |
ttXlaTblDesc_t* |
Table to search |
keys |
void* |
A record in the defined structure for the table
Only those columns of the keys record that are part of the primary key for the table are examined. |
result |
void* |
Where the located record is copied
If no record exists with the matching key columns, an error is returned. |
maxsize |
SQLINTEGER |
Size of the largest record that can fit into the result buffer |
retsize |
SQLINTEGER* |
Actual size of the record |
Returns SQL_SUCCESS
if call is successful. Otherwise, use ttXlaError
to report the error.
This example looks up a record given a pair of integer key values. Before this call, table
should describe the desired table and keybuffer
contains a record with the key columns set.
char keybuffer[100]; char recbuffer[2000]; ttXlaTableDesc_t table; SQLINTEGER recordSize; rc = ttXlaLookup(xlahandle, &table, keybuffer, recbuffer, sizeof (recbuffer), &recordSize);
This function is part of XLA replication functionality and is not appropriate for use in a typical XLA application.
Rolls back the current transaction being applied on the transaction log handle. You can call this routine to respond to transient errors (timeout or deadlock) reported by ttXlaApply
.
See "Handling timeout and deadlock errors" for a discussion about using this function.
Returns SQL_SUCCESS
if call is successful. Otherwise, use ttXlaError
to report the error.
This function is part of XLA replication functionality and is not appropriate for use in a typical XLA application.
When using XLA as a replication mechanism, this function verifies that the named table in the ttXlaTblDesc_t
structure received from a master database is compatible with a subscriber database or database associated with the transaction log handle. The compat
parameter indicates whether the tables are compatible.
See "Checking table compatibility between databases" for a discussion about using this function.
SQLRETURN ttXlaTableCheck(ttXlaHandle_h handle, ttXlaTblDesc_t* table, ttXlaColDesc_t* columns, out SQLINTEGER* compat)
Parameter | Type | Description |
---|---|---|
handle |
ttXlaHandle_h |
Transaction log handle for the database |
table |
ttXlaTblDesc_t* |
Table description |
columns |
ttXlaColDesc_t* |
Column description for the table |
compat |
SQLINTEGER* |
Compatibility information:
|
Returns SQL_SUCCESS
if call is successful. Otherwise, use ttXlaError
to report the error.
This example checks the compatibility of a table:
SQLINTEGER compat; ttXlaTblDesc_t table; ttXlaColDesc_t columns[20]; /* * Get the desired table and column definitions into * the variables "table" and "columns" */ rc = ttXlaTableCheck(xlahandle, &table, columns, &compat); if (compat) { /* Compatible */ } else { /* * Not compatible or some other error occurred */ }
This section describes the C data structures used by the XLA functions described in this chapter. These structures are defined in the following file:
install_dir
/include/tt_xla.h
You must include this file when building your XLA application.
Table 9-1 Summary of C data structures
C data structure | Description |
---|---|
Describes the record type. Used at the beginning of records returned by XLA. |
|
Describes an update record. |
|
Describes XLA version information returned by |
|
Describes table information returned by |
|
Describes table version returned by |
|
Describes table column information returned by |
|
Describes a log record identifier used by bookmarks. This structure is used by the |
|
Describes a log record identifier used by an XLA bookmark. |
Most C data structures begin with a standard header that describes the data record type and length. The standard header has the type ttXlaNodeHdr_t
.
This header has the following fields.
Field | Type | Description |
---|---|---|
nodeType |
char |
The type of record:
|
byteOrder |
char |
Byte order of the record:
|
length |
SQLUINTEGER |
Total length of record, including all attachments |
This structure describes an update operation to a single row (or tuple) in the database. Each update record returned by a ttXlaNextUpdate
or ttXlaNextUpdateWait
function begins with a fixed length ttXlaUpdateDesc_t
header followed by zero to two rows from the database. The row data differs depending on the record type reported in the ttXlaUpdateDesc_t
header:
No rows are present in a COMMITONLY
record.
One row is present in INSERTTUP
or DELETETUP
.
Two rows are present in an UPDATETUP
record to report the row data before and after the update, respectively.
Special format rows are present in CREATAB
, DROPTAB
, CREAIND
, DROPIND
, CREATVIEW
, DROPVIEW
, CREATSEQ
, DROPSEQ
, CREATSYN
, DROPSYN
, ADDCOLS
, and DRPCOLS
records, which are described in "Special update data formats".
The flags
field is a bit-map of special options for the record update.
The connID
field identifies the ODBC connection handle that initiated the update. This value can be used to determine if updates came from the same connection.
A separate commit XLA record is generated when a call to the ttApplicationContext
procedure is not followed by an operation that generates an XLA record. See "Passing application context" for a description of the ttApplicationContext
procedure.
XLA cannot receive notification of the following:
CREATE VIEW
or DROP VIEW
for a non-materialized view
CREATE GLOBAL TEMPORARY TABLE
or DROP TABLE
for a temporary table
The only XLA records that can be generated from an ALTER TABLE
operation are of the following types:
ADDCOLS
or DRPCOLS
when columns are added or dropped
CREAIND
or DROPIND
when a unique attribute of a column is modified
While sequence creates (CREATESEQ
) and drops (DROPSEQ
) are visible through XLA, sequence increments are not.
All deletes resulting from cascading deletes and aging are visible through XLA. The flags
value (discussed in the following table) indicates when deletes are due to cascading or aging.
The fields of the update header defined by ttXlaUpdateDesc_t
are as follows.
Field | Type | Description |
---|---|---|
header |
ttXlaNodeHdr_t |
Standard data header |
type |
SQLUSMALLINT |
Record type:
|
flags |
SQLUSMALLINT |
Special options on record update:
If the value of a specific column is 0, it indicates that column does not have a default value. The defaults for all nonzero values are concatenated in a string and are presented in order, with the array value indicating the length of the default value. For example, three columns with defaults 1 of type Decimal values for each of these TT_UPDCOMMIT 1 TT_UPDFIRST 2 TT_UPDREPL 4 TT_UPDCOLS 8 TT_UPDDEFAULT 64 TT_CASCDEL 256 TT_AGING 512 |
contextOffset |
SQLUINTEGER |
Offset to application-provided context value
This value is 0 if there is no context. A nonzero value indicates the location of the context relative to the beginning of the XLA record. |
connID |
SQLUBIGINT |
Connection ID owning the transaction |
sysTableID |
SQLUBIGINT |
System-provided identifier of the affected table |
userTableID |
SQLUBIGINT |
Application-defined table ID of the affected table |
tranID |
SQLUBIGINT |
Read-only, system-provided transaction identifier |
LSN |
tt_LSN_t |
Transaction log record identifier of this operation, used for diagnostics |
tuple1 |
SQLUINTEGER |
Length of first row (tuple), or zero |
tuple2 |
SQLUINTEGER |
Length of second row (tuple), or zero |
Note:
Be aware thattt_LSN_t
, particularly the logFile
and logOffset
fields, is used differently than in earlier releases, referring to log record identifiers rather than sequentially increasing LSNs. See the note in "tt_LSN_t".The data contained in an update record follows the ttXlaTblDesc_t
header. This section describes the data formats for the special update records related to specific SQL operations.
For a CREATE TABLE
operation, the special row value consists of the ttXlaTblDesc_t
record describing the new table, followed by the ttXlaColDesc_t
records that describe each column.
For an ALTER TABLE
operation, the special row value consists of a ttXlaDropTableTup_t
or ttXlaAddColumnTup_t
value, followed by a ttXlaColDesc_t
record that describes the column.
For a DROP TABLE
operation, the row value is as follows.
Field | Type | Description |
---|---|---|
tblName |
char(31) |
Name of the dropped table |
tblOwner |
char(31) |
Owner of the dropped table |
For a TRUNCATE TABLE
operation, the row value is as follows.
Field | Type | Description |
---|---|---|
tblName |
char(31) |
Name of the truncated table |
tblOwner |
char(31) |
Owner of the truncated table |
For a CREATE INDEX
operation, the row value is as follows.
Field | Type | Description |
---|---|---|
tblName |
char(31) |
Name of the table on which the index is defined |
tblOwner |
char(31) |
Owner of the table on which the index is defined |
ixName |
char(31) |
Name of the new index |
flag |
char(31) |
Index flag:
|
nixcols |
SQLUINTEGER |
Number of indexed columns |
ixColsSys |
SQLUINTEGER(16) |
Indexed column numbers using system numbers |
ixColsUser |
SQLUINTEGER(16) |
Indexed column numbers using user-defined column IDs |
ixType |
char |
Type of index:
|
ixUnique |
char |
Uniqueness of index:
|
pages |
SQLUINTEGER |
Number of pages for hash indexes |
For a DROP INDEX
operation, the row value is as follows.
Field | Type | Description |
---|---|---|
tblName |
char(31) |
Name of the table on which the index was dropped |
tblOwner |
char(31) |
Owner of the table on which the index was dropped |
ixName |
char(31) |
Name of the dropped index |
For an ADD COLUMN
operation, the row value is as follows.
Field | Type | Description |
---|---|---|
ncols |
SQLUINTEGER |
Number of additional columns |
Following this special row are the ttXlaColDesc_t
records describing the new columns.
For a DROP COLUMN
operation, the row value is as follows.
Field | Type | Description |
---|---|---|
ncols |
SQLUINTEGER |
Number of dropped columns |
Following this special row is an array of ttXlaColDesc_t
records describing the columns that were dropped.
For a CREATE SEQUENCE
operation, the row value is as follows.
Field | Type | Description |
---|---|---|
sqName |
char(31) |
Name of sequence |
sqOwner |
char(31) |
Owner of sequence |
cycle |
char |
Cycle flag
Indicates whether the sequence number generator continues to generate numbers after it reaches the maximum or minimum value:
|
minval |
SQLBIGINT |
Minimum value of sequence |
maxval |
SQLBIGINT |
Maximum value of sequence |
incr |
SQLBIGINT |
Increment between sequence numbers
Positive numbers indicate an ascending sequence and negative numbers indicate a descending sequence. In a descending sequence, the range goes from |
For a DROP SEQUENCE
operation, the row value is as follows.
Field | Type | Description |
---|---|---|
sqName |
char(31) |
Name of sequence |
sqOwner |
char(31) |
Owner of sequence |
For a CREATE VIEW
operation, the row value is as follows.
Note:
This applies to either materialized or non-materialized views.Field | Type | Description |
---|---|---|
vwName |
char(31) |
Name of view |
vwOwner |
char(31) |
Owner of view |
sysTableID |
SQLUBIGINT |
System table ID stored in SYS.TABLES |
For a DROP VIEW
operation, the row value is as follows.
Note:
This applies to either materialized or non-materialized views.Field | Type | Description |
---|---|---|
vwName |
char(31) |
Name of view |
vwOwner |
char(31) |
Owner of view |
For a CREATE SYNONYM
operation, the row value is as follows.
Field | Type | Description |
---|---|---|
synName |
char(31) |
Name of synonym |
synOwner |
char(31) |
Owner of synonym |
objName |
char(31) |
Name of object the synonym points to |
objOwner |
char(31) |
Owner of object the synonym points to |
isPublic |
char |
Indicates whether the synonym is public:
|
isReplace |
char |
Indicates whether the synonym was created using CREATE OR REPLACE :
|
For a DROP SYNONYM
operation, the row value is as follows.
Field | Type | Description |
---|---|---|
synName |
char(31) |
Name of synonym |
synOwner |
char(31) |
Owner of synonym |
isPublic |
char |
Indicates whether the synonym is public:
|
The description of the SET TABLE ID
operation uses the previously assigned application table identifier in the main part of the update record and provides the new value of the application table identifier in the following special row.
Field | Type | Description |
---|---|---|
newID |
SQLUBIGINT |
New user-defined table ID |
See "Retrieving update records from the transaction log" and "Inspecting record headers and locating row addresses" for a detailed discussion on obtaining update records and inspecting the contents of ttXlaUpdateDesc_t
headers. Below is a summary of these procedures.
The update header is immediately followed by the row data. The row data is stored in an internal format with the offsets given in the ttXlaColDesc_t
structure returned by ttXlaGetColumnInfo
.
You can locate the address of the row data by adding the address of the update header to its size.
For example:
char* Row = (char*)&ttXlaUpdateDesc_t + sizeof(ttXlaUpdateDesc_t);
For UPDATETUP
records, there are two rows of data following the ttXlaUpdateDesc_t
header. The first row contains the data before the update, and the second row the data after the update.
Since the new row is right after the old row, you can calculate its address by adding the address of the old row to its length (tuple1
).
For example:
char* oldRow = (char*)&ttXlaUpdateDesc_t + sizeof(ttXlaUpdateDesc_t); char* newRow = oldRow + ttXlaUpdateDesc_t.tuple1;
See "ttXlaColDesc_t" for details on how to access the column data in a returned row.
To permit future extensions to XLA, a version structure ttXlaVersion_t
describes the current XLA version and structure byte order. This structure is returned by the ttXlaGetVersion
function.
This structure has the following fields:
Field | Type | Description |
---|---|---|
header |
ttXlaNodeHdr_t |
Standard data header |
hardware |
char(16) |
Name of hardware platform |
wordSize |
SQLUINTEGER |
Native word size (32 or 64 bits) |
TTMajor |
SQLUINTEGER |
TimesTen major version |
TTMinor |
SQLUINTEGER |
TimesTen minor version |
TTPatch |
SQLUINTEGER |
TimesTen point release number |
OS |
char(16) |
Name of operating system |
OSMajor |
SQLUINTEGER |
Operating system major version |
OSMinor |
SQLUINTEGER |
Operating system minor version |
Table information is portrayed through the ttXlaTblDesc_t
structure. This structure is returned by the ttXlaGetTableInfo
function.
This structure has the following fields:
Field | Type | Description |
---|---|---|
header |
ttXlaNodeHdr_t |
Standard data header |
tblName |
char(31) |
Name of the table, null-terminated |
tblOwner |
char(31) |
Owner of the table, null-terminated |
sysTableID |
SQLUBIGINT |
Unique system-defined table identifier |
userTableId |
SQLUBIGINT |
User-defined table identifier |
columns |
SQLUINTEGER |
Number of columns |
width |
SQLUINTEGER |
Inline row size |
nPrimCols |
SQLUINTEGER |
Number of primary columns |
primColsSys |
SQLUINTEGER(16) |
System primary key column numbers |
primColsUser |
SQLUINTEGER(16) |
User-defined primary key column numbers |
The inline row size includes space for all fixed-width columns, null column flags, and pointer information for variable-length columns. Each varying-length column occupies four bytes of inline row space.
Note the following if the table has a declared primary key:
The nPrimCols
value is greater than 0.
The primColsSys
array contains the column numbers of the primary key, in the same order in which they were originally declared with the CREATE TABLE
statement.
The primColsUser
array contains the corresponding application-specified column identifiers.
This data structure contains the table version number and ttXlaTblDesc_t
. It is returned by ttXlaVersionTableInfo
. This structure has the following fields:
Field | Type | Description |
---|---|---|
tblDesc |
ttXlaTblDesc_t |
Table description |
tblVer |
SQLBIGINT |
System-generated table version number |
Column information is given through this structure, which is returned by the ttXlaGetColumnInfo
function.
The structure has the following fields:
Field | Type | Description |
---|---|---|
header |
ttXlaNodeHdr_t |
Standard data header |
colName [tt_NameLenMax] |
char |
Name of the column |
pad0 |
SQLUINTEGER |
Pad to four-byte boundary |
sysColNum |
SQLUINTEGER |
Ordinal number of the column as determined when the table is created or subsequently altered
This is the same as the corresponding |
userColNum |
SQLUINTEGER |
Ordinal number of the column if optionally specified by the user
This is zero or a column number specified through the |
dataType |
SQLUINTEGER |
Structure in ODBC TTXLA_* code
|
size |
SQLUINTEGER |
Maximum or basic size of column |
offset |
SQLUINTEGER |
Offset to fixed-length part of column |
nullOffset |
SQLUINTEGER |
Offset to null byte, or zero if not nullable |
precision |
SQLSMALLINT |
Numeric precision for decimal types |
scale |
SQLSMALLINT |
Numeric scale for decimal types |
flags |
SQLUINTEGER |
Column flag:
|
The procedures for obtaining a ttXlaColDesc_t
structure and inspecting its contents are described in "Inspecting column data". Below is a summary of these procedures.
The ttXlaColDesc_t
structure is returned by the ttXlaGetColumnInfo
function. This structure contains the metadata needed to access column information in a particular table. For example, you can use the offset
field to locate specific column data in the row or rows returned in an update record after the ttXlaColDesc_t
structure. By adding the offset
to the address of a returned row, you can locate the address to the column value. You can then cast this value to the corresponding C types according to the dataType
field, or pass it to one of the conversion routines described in "Converting complex data types".
TimesTen row data consists of fixed-length data followed by any variable-length data.
For fixed length column data, ttXlaColDesc_t
returns the offset
and size
of the column data. The offset
is relative to the beginning of the fixed part of the record. See Example 9-1 below.
For variable-length column data (VARCHAR2
, NVARCHAR2
, and VARBINARY
), offset
is an address that points to a four-byte offset value. By adding the offset address to the offset value, you can obtain the address of the column data in the variable-length portion of the row. The first n
bytes at this location is the length of the data, followed by the actual data (where n
is 4 on 32-bit platforms or 8 on 64-bit platforms). For variable-length data, the returned size value is the maximum allowable column size. See Example 9-1 below.
For columns that can have null values, nullOffset
points to a null byte in the record. This value is 1 if the column is null, or 0 if it is not null. See "Detecting null values" for a discussion.
The flags
bits define whether the column is nullable, part of a primary key, or stored out of line.
The sysColNum
value is the system column number to assign to the column. This value begins with 1 for the first column.
You can subscribe to tables containing LOB columns, but information about the LOB value itself is unavailable.
ttXlaGetColumnInfo
returns information about LOB columns.
Columns containing LOBs are reported as empty (zero length) or null (if the value is actually NULL
). In this way, you can tell the difference between a null column and a non-null column.
Example 9-1 Copying and printing a VARCHAR2 string
For fixed-length column data, the address of a column is the offset
value in the ttXlaColDesc_t
structure, plus the address of the row as follows:
ttXlaColDesc_t colDesc; void* pColVal = colDesc->offset + row;
The value of the column can be obtained by dereferencing this pointer using a type pointer that corresponds to the data type. For example, for SQL_INTEGER
, the ODBC type is SQLINTEGER
and the value of the column can be obtained by the following:
*((SQLINTEGER*) pColVal))
In the case of variable-length column data, the pColVal
calculated above is the address of a four-byte offset value. Adding this offset value to the address of pColVal
provides a pointer to the beginning of the variable-length column data. Assuming the operation is performed on a 64-bit platform, the first eight bytes at this location is the length of this data (var_len
), followed by the actual data (var_data
).
In this example, a VARCHAR
string is copied and printed.
tt_ptrint* var_len = (tt_ptrint*)((char*)pColVal + *((int*)pColVal)); char* var_data = (char*)(var_len+1); char* buffer = malloc(*var_len+1); memcpy(buffer,var_data,*var_len); buffer[*var_len] = (char)NULL; /* NULL terminate the string */ printf("%s\n",buffer); free(buffer);
Description of log record identifier used by bookmarks. This structure is used by the ttXlaUpdateDesc_t
structure.
Field | Type | Description |
---|---|---|
logFile |
SQLUBIGINT |
Higher order portion of log record identifier |
logOffset |
SQLUBIGINT |
Lower order portion of log record identifier |
Note:
ThelogFile
and logOffset
field names are retained for backward compatibility, although their usage has changed. In previous releases the values referred to LSNs, which increased sequentially, and the values had very specific meanings, indicating the log file number plus byte offset. Now they refer to log record identifiers, which are more abstract and do not have a direct relationship to the log file number and byte offset. All you can assume about a sequence of log record identifiers is that a log record identifier B read at a later time than a log record identifier A has a higher value.Description of a log record identifier used by bookmarks. This structure is returned by the ttXlaGetLSN
function and used by the ttXlaSetLSN
function.
The checksum
is specific to an XLA handle to ensure that every log record identifier is related to a known XLA connection.
Field | Type | Description |
---|---|---|
checksum |
SQLUINTEGER |
Checksum used to ensure that it is a valid log record identifier handle |
xid |
SQLUSMALLINT |
Transaction ID |
logFile |
SQLUBIGINT |
Higher order portion of log record identifier |
logOffset |
SQLUBIGINT |
Lower order portion of log record identifier |
Note:
ThelogFile
and logOffset
field names are retained for backward compatibility, although their usage has changed. In previous releases the values referred to LSNs, which increased sequentially, and the values had very specific meanings, indicating the log file number plus byte offset. Now they refer to log record identifiers, which are more abstract and do not have a direct relationship to the log file number and byte offset. All you can assume about a sequence of log record identifiers is that a log record identifier B read at a later time than a log record identifier A has a higher value.