Update Statistics code in AlterTableConstantAction should use execute
transaction rather than compile transaction
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Key: DERBY-4048
URL: https://issues.apache.org/jira/browse/DERBY-4048
Project: Derby
Issue Type: Improvement
Components: SQL
Affects Versions: 10.5.0.0
Reporter: Mamta A. Satoor
DERBY-269 provided a new stored procedure SYSCS_UTIL.SYSCS_UPDATE_STATISTICS to
update the statistics. The code to do the work was added in
AlterTableConstantAction and the name of new method in that class is
updateStatistics(Activation activation). This code was copied from an existing
unused class execute/UpdateStatisticsConstantAction.java(that unused class has
been removed from Derby code).
The copied code in AlterTableConstantAction:updateStatistics gets compile
transaction as shown below to do the work of updating the statistics.
TransactionController tc = lcc.getTransactionCompile();
The javadoc for LangaugeConnectionContext for getTransactionCompile says
following
/**
Get the transaction controller to use with this language
connection
context at compile time.
*/
TransactionController getTransactionCompile();
I think we should be using TransactionController tc =
lcc.getTransactionExecute() to do the work since we are not in the compile
phase. The rest of the code in AlterTableConstantAction uses
lcc.getTransactionExecute to get the transaction controller.
I will make the changes in AlterTableConstantAction.updateStatistics to use
getTransactionExecute and will run the existing tests to make sure nothing
breaks.
I ran into this issue of getTransactionExecute vs getTransactionCompile while
working on DERBY-3788 (provide a zero-admin way of updating the statistics).
While trying to run the statistics inline duirn the compile phase of a SELECT
query, I ran into exception that statistics can't be updated because we are in
read-only mode. But if I change the AlterTableConstantAction to use
getTransactionExecute, then I do not run into the read-only mode exception.
Please let me know if anyone has any comments on this. I will run the existing
tests and if no failures, then I will go ahead and commit the change of using
getTransactionExecute rather than getTransactionCompile in
AlterTableConstantAction:updateStatistics
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