- 12 Functions and Operators
- 12.1 Function and Operator Reference
- 12.2 Type Conversion in Expression Evaluation
- 12.3 Operators
- 12.4 Control Flow Functions
- 12.5 String Functions
- 12.6 Numeric Functions and Operators
- 12.7 Date and Time Functions
- 12.8 What Calendar Is Used By MySQL?
- 12.9 Full-Text Search Functions
- 12.10 Cast Functions and Operators
- 12.11 XML Functions
- 12.12 Bit Functions
- 12.13 Encryption and Compression Functions
- 12.14 Information Functions
- 12.15 GTID Functions
- 12.16 Miscellaneous Functions
- 12.17 Functions and Modifiers for Use with GROUP BY Clauses
- 12.18 Spatial Extensions
- 12.19 Precision Math
The functions described in this section are used with GTID-based replication (available in MySQL 5.6.5 and later). For more information about GTIDs and how these functions are used, see Section 16.1.3, “Replication with Global Transaction Identifiers”.
The union of two GTID sets is simply their string representations joined together with an interposed comma. In other words, you can define a very simple function for obtaining the union of two GTID sets like this:
CREATE FUNCTION GTID_UNION(g1 TEXT, g2 TEXT)
RETURNS TEXT DETERMINISTIC
RETURN CONCAT(g1,',',g2);
Table 12.19. GTID Functions
| Name | Description |
|---|---|
GTID_SUBSET() | Return true if all GTIDs in subset are also in set; otherwise false. |
GTID_SUBTRACT() | Return all GTIDs in set that are not in subset. |
SQL_THREAD_WAIT_AFTER_GTIDS()(deprecated 5.6.9) | OBSOLETE: Replaced by WAIT_UNTIL_SQL_THREAD_AFTER_GTIDS() |
WAIT_UNTIL_SQL_THREAD_AFTER_GTIDS() | Wait until the slave SQL thread has executed all the given GTIDs. Returns: the number of events that were executed (or NULL, if GTID mode is not enabled). |
Given two sets of global transaction IDs
subsetandset, returns true if all GTIDs insubsetare also inset. Returns false otherwise.This function was added in MySQL 5.6.5.
Given two sets of global transaction IDs
subsetandset, returns only those GTIDs fromsetthat are not insubset.This function was added in MySQL 5.6.5.
SQL_THREAD_WAIT_AFTER_GTIDS(gtid_set[,timeout])SQL_THREAD_WAIT_AFTER_GTIDS()was added in MySQL 5.6.5, and replaced byWAIT_UNTIL_SQL_THREAD_AFTER_GTIDS()in MySQL 5.6.9. (Bug #14775984)For more information, see Section 16.1.3, “Replication with Global Transaction Identifiers”.
WAIT_UNTIL_SQL_THREAD_AFTER_GTIDS(gtid_set[,timeout])Wait until the slave SQL thread has executed all of the transactions whose global transaction identifiers are contained in
gtid_set(see Section 16.1.3.1, “GTID Concepts”, for a definition of “GTID sets”), or untiltimeoutseconds have elapsed, whichever occurs first.timeoutis optional; the default timeout is 0 seconds, in which case the master simply waits until all of the transactions in the GTID set have been executed.Prior to MySQL 5.6.9,
WAIT_UNTIL_SQL_THREAD_AFTER_GTIDS()was namedSQL_THREAD_WAIT_AFTER_GTIDS(). (Bug #14775984)For more information, see Section 16.1.3, “Replication with Global Transaction Identifiers”.
mysql>
SELECT WAIT_UNTIL_SQL_THREAD_AFTER_GTIDS('3E11FA47-71CA-11E1-9E33-C80AA9429562:1-5');-> 5The return value is the number of transactional events that were executed. Prior to MySQL 5.6.8, this function behaved unpredictably if no timeout was set and it was invoked while GTID-based replication was not active; in MySQL 5.6.8 and later, the function returns
NULLwhenevergtid_modeisOFF. (Bug #14640065)
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