Further review of xact.c state machine for nested transactions. Fix
problems with starting subtransactions inside already-failed transactions. Clean up some comments.
This commit is contained in:
Tom Lane
parent
e15d0bb8e8
commit
b6197fe069
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@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/access/transam/xact.c,v 1.169 2004/07/01 00:49:42 tgl Exp $
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* $PostgreSQL: pgsql/src/backend/access/transam/xact.c,v 1.170 2004/07/01 20:11:02 tgl Exp $
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*
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* NOTES
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* Transaction aborts can now occur two ways:
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@ -196,6 +196,7 @@ static void StartSubTransaction(void);
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static void CommitSubTransaction(void);
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static void AbortSubTransaction(void);
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static void CleanupSubTransaction(void);
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static void StartAbortedSubTransaction(void);
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static void PushTransaction(void);
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static void PopTransaction(void);
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@ -317,7 +318,7 @@ IsAbortedTransactionBlockState(void)
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TransactionState s = CurrentTransactionState;
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if (s->blockState == TBLOCK_ABORT ||
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s->blockState == TBLOCK_SUBABORT)
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s->blockState == TBLOCK_SUBABORT)
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return true;
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return false;
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@ -1579,10 +1580,9 @@ StartTransactionCommand(void)
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break;
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/*
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* This is the case when are somewhere in a transaction block
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* This is the case when we are somewhere in a transaction block
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* and about to start a new command. For now we do nothing
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* but someday we may do command-local resource
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* initialization.
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* but someday we may do command-local resource initialization.
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*/
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case TBLOCK_INPROGRESS:
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case TBLOCK_SUBINPROGRESS:
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@ -1699,7 +1699,9 @@ CommitTransactionCommand(void)
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/*
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* We were just issued a BEGIN inside a transaction block.
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* Start a subtransaction.
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* Start a subtransaction. (BeginTransactionBlock already
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* did PushTransaction, so as to have someplace to put the
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* SUBBEGIN state.)
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*/
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case TBLOCK_SUBBEGIN:
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StartSubTransaction();
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@ -1711,8 +1713,7 @@ CommitTransactionCommand(void)
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* Start a subtransaction, and put it in aborted state.
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*/
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case TBLOCK_SUBBEGINABORT:
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StartSubTransaction();
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AbortSubTransaction();
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StartAbortedSubTransaction();
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s->blockState = TBLOCK_SUBABORT;
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break;
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@ -1724,7 +1725,7 @@ CommitTransactionCommand(void)
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break;
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/*
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* We where issued a COMMIT command, so we end the current
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* We were issued a COMMIT command, so we end the current
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* subtransaction and return to the parent transaction.
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*/
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case TBLOCK_SUBEND:
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@ -1740,7 +1741,7 @@ CommitTransactionCommand(void)
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break;
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/*
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* We are ending a subtransaction that aborted nicely,
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* We are ending an aborted subtransaction via ROLLBACK,
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* so the parent can be allowed to live.
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*/
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case TBLOCK_SUBENDABORT_OK:
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@ -1750,9 +1751,8 @@ CommitTransactionCommand(void)
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break;
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/*
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* We are ending a subtransaction that aborted in a unclean
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* way (e.g. the user issued COMMIT in an aborted subtrasaction.)
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* Abort the subtransaction, and abort the parent too.
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* We are ending an aborted subtransaction via COMMIT.
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* End the subtransaction, and abort the parent too.
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*/
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case TBLOCK_SUBENDABORT_ERROR:
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CleanupSubTransaction();
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@ -1791,7 +1791,7 @@ AbortCurrentTransaction(void)
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break;
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/*
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* If we are in the TBLOCK_BEGIN it means something screwed up
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* If we are in TBLOCK_BEGIN it means something screwed up
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* right after reading "BEGIN TRANSACTION" so we enter the
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* abort state. Eventually an "END TRANSACTION" will fix
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* things.
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@ -1803,10 +1803,10 @@ AbortCurrentTransaction(void)
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break;
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/*
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* This is the case when are somewhere in a transaction block
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* which aborted so we abort the transaction and set the ABORT
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* state. Eventually an "END TRANSACTION" will fix things and
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* restore us to a normal state.
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* This is the case when we are somewhere in a transaction block
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* and we've gotten a failure, so we abort the transaction and
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* set up the persistent ABORT state. We will stay in ABORT
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* until we get an "END TRANSACTION".
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*/
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case TBLOCK_INPROGRESS:
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AbortTransaction();
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@ -1817,7 +1817,7 @@ AbortCurrentTransaction(void)
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/*
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* Here, the system was fouled up just after the user wanted
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* to end the transaction block so we abort the transaction
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* and put us back into the default state.
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* and return to the default state.
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*/
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case TBLOCK_END:
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AbortTransaction();
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@ -1852,10 +1852,7 @@ AbortCurrentTransaction(void)
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*/
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case TBLOCK_SUBBEGIN:
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case TBLOCK_SUBBEGINABORT:
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PushTransaction();
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s = CurrentTransactionState; /* changed by push */
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StartSubTransaction();
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AbortSubTransaction();
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StartAbortedSubTransaction();
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s->blockState = TBLOCK_SUBABORT;
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break;
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@ -2092,8 +2089,10 @@ CallEOXactCallbacks(bool isCommit)
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* transaction block support
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* ----------------------------------------------------------------
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*/
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/*
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* BeginTransactionBlock
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* This executes a BEGIN command.
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*/
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void
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BeginTransactionBlock(void)
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@ -2102,7 +2101,7 @@ BeginTransactionBlock(void)
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switch (s->blockState) {
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/*
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* We are inside a transaction, so allow a transaction block
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* We are not inside a transaction block, so allow one
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* to begin.
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*/
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case TBLOCK_STARTED:
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@ -2149,6 +2148,7 @@ BeginTransactionBlock(void)
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/*
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* EndTransactionBlock
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* This executes a COMMIT command.
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*/
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void
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EndTransactionBlock(void)
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@ -2176,9 +2176,9 @@ EndTransactionBlock(void)
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break;
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/*
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* here, we are in a transaction block which aborted and since the
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* AbortTransaction() was already done, we do whatever is needed
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* and change to the special "END ABORT" state. The upcoming
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* here, we are in a transaction block which aborted. Since the
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* AbortTransaction() was already done, we need only
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* change to the special "END ABORT" state. The upcoming
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* CommitTransactionCommand() will recognise this and then put us
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* back in the default state.
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*/
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@ -2189,7 +2189,8 @@ EndTransactionBlock(void)
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/*
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* here we are in an aborted subtransaction. Signal
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* CommitTransactionCommand() to clean up and return to the
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* parent transaction.
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* parent transaction. Since the user said COMMIT, we must
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* fail the parent transaction.
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*/
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case TBLOCK_SUBABORT:
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s->blockState = TBLOCK_SUBENDABORT_ERROR;
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@ -2209,7 +2210,7 @@ EndTransactionBlock(void)
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s->blockState = TBLOCK_ENDABORT;
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break;
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/* These cases are invalid. Reject them altogether. */
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/* these cases are invalid. */
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case TBLOCK_DEFAULT:
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case TBLOCK_BEGIN:
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case TBLOCK_ENDABORT:
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@ -2227,6 +2228,7 @@ EndTransactionBlock(void)
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/*
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* UserAbortTransactionBlock
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* This executes a ROLLBACK command.
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*/
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void
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UserAbortTransactionBlock(void)
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@ -2244,7 +2246,10 @@ UserAbortTransactionBlock(void)
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s->blockState = TBLOCK_ENDABORT;
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break;
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/* Ditto, for a subtransaction. */
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/*
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* Ditto, for a subtransaction. Here it is okay to allow the
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* parent transaction to continue.
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*/
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case TBLOCK_SUBABORT:
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s->blockState = TBLOCK_SUBENDABORT_OK;
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break;
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@ -2336,8 +2341,8 @@ AbortOutOfAnyTransaction(void)
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case TBLOCK_SUBBEGIN:
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case TBLOCK_SUBBEGINABORT:
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/*
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* Just starting a new transaction -- return to parent.
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* FIXME -- Is this correct?
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* We didn't get as far as starting the subxact, so there's
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* nothing to abort. Just pop back to parent.
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*/
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PopTransaction();
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s = CurrentTransactionState; /* changed by pop */
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@ -2353,6 +2358,7 @@ AbortOutOfAnyTransaction(void)
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case TBLOCK_SUBABORT:
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case TBLOCK_SUBENDABORT_OK:
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case TBLOCK_SUBENDABORT_ERROR:
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/* As above, but AbortSubTransaction already done */
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CleanupSubTransaction();
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PopTransaction();
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s = CurrentTransactionState; /* changed by pop */
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@ -2521,6 +2527,8 @@ CommitSubTransaction(void)
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AtSubCommit_Portals(s->parent->transactionIdData);
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DeferredTriggerEndSubXact(true);
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s->state = TRANS_COMMIT;
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/* Mark subtransaction as subcommitted */
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CommandCounterIncrement();
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RecordSubTransactionCommit();
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@ -2642,6 +2650,49 @@ CleanupSubTransaction(void)
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s->state = TRANS_DEFAULT;
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}
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/*
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* StartAbortedSubTransaction
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*
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* This function is used to start a subtransaction and put it immediately
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* into aborted state. The end result should be equivalent to
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* StartSubTransaction immediately followed by AbortSubTransaction.
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* The reason we don't implement it just that way is that many of the backend
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* modules aren't designed to handle starting a subtransaction when not
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* inside a valid transaction. Rather than making them all capable of
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* doing that, we just omit the paired start and abort calls in this path.
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*/
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static void
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StartAbortedSubTransaction(void)
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{
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TransactionState s = CurrentTransactionState;
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if (s->state != TRANS_DEFAULT)
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elog(WARNING, "StartAbortedSubTransaction and not in default state");
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s->state = TRANS_START;
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/*
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* We don't bother to generate a new Xid, so the end state is not
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* *exactly* like we had done a full Start/AbortSubTransaction...
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*/
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s->transactionIdData = InvalidTransactionId;
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/* Make sure currentUser is reasonably valid */
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Assert(s->parent != NULL);
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s->currentUser = s->parent->currentUser;
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/*
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* Initialize only what has to be there for CleanupSubTransaction to work.
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*/
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AtSubStart_Memory();
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s->state = TRANS_ABORT;
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AtSubAbort_Memory();
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ShowTransactionState("StartAbortedSubTransaction");
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}
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/*
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* PushTransaction
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* Set up transaction state for a subtransaction
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@ -2672,6 +2723,7 @@ PushTransaction(void)
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*/
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s->transactionIdData = p->transactionIdData;
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s->curTransactionContext = p->curTransactionContext;
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s->currentUser = p->currentUser;
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CurrentTransactionState = s;
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}
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@ -132,6 +132,65 @@ SELECT * FROM barbaz; -- should have 1
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1
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(1 row)
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-- check that starting a subxact in a failed xact or subxact works
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BEGIN;
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SELECT 0/0; -- fail the outer xact
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ERROR: division by zero
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BEGIN;
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SELECT 1; -- this should NOT work
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ERROR: current transaction is aborted, commands ignored until end of transaction block
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COMMIT;
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SELECT 1; -- this should NOT work
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ERROR: current transaction is aborted, commands ignored until end of transaction block
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BEGIN;
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SELECT 1; -- this should NOT work
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ERROR: current transaction is aborted, commands ignored until end of transaction block
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ROLLBACK;
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SELECT 1; -- this should NOT work
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ERROR: current transaction is aborted, commands ignored until end of transaction block
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COMMIT;
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SELECT 1; -- this should work
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?column?
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----------
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1
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(1 row)
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BEGIN;
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BEGIN;
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SELECT 1; -- this should work
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?column?
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----------
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1
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(1 row)
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SELECT 0/0; -- fail the subxact
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ERROR: division by zero
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SELECT 1; -- this should NOT work
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ERROR: current transaction is aborted, commands ignored until end of transaction block
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BEGIN;
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SELECT 1; -- this should NOT work
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ERROR: current transaction is aborted, commands ignored until end of transaction block
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ROLLBACK;
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BEGIN;
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SELECT 1; -- this should NOT work
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ERROR: current transaction is aborted, commands ignored until end of transaction block
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COMMIT;
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SELECT 1; -- this should NOT work
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ERROR: current transaction is aborted, commands ignored until end of transaction block
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ROLLBACK;
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SELECT 1; -- this should work
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?column?
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----------
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1
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(1 row)
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COMMIT;
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SELECT 1; -- this should work
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?column?
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----------
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1
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(1 row)
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DROP TABLE foo;
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DROP TABLE baz;
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DROP TABLE barbaz;
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@ -96,6 +96,38 @@ COMMIT;
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SELECT * FROM foo; -- should have 1 and 3
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SELECT * FROM barbaz; -- should have 1
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-- check that starting a subxact in a failed xact or subxact works
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BEGIN;
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SELECT 0/0; -- fail the outer xact
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BEGIN;
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SELECT 1; -- this should NOT work
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COMMIT;
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SELECT 1; -- this should NOT work
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BEGIN;
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SELECT 1; -- this should NOT work
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ROLLBACK;
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SELECT 1; -- this should NOT work
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COMMIT;
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SELECT 1; -- this should work
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BEGIN;
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BEGIN;
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SELECT 1; -- this should work
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SELECT 0/0; -- fail the subxact
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SELECT 1; -- this should NOT work
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BEGIN;
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SELECT 1; -- this should NOT work
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ROLLBACK;
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BEGIN;
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SELECT 1; -- this should NOT work
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COMMIT;
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SELECT 1; -- this should NOT work
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ROLLBACK;
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SELECT 1; -- this should work
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COMMIT;
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SELECT 1; -- this should work
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DROP TABLE foo;
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DROP TABLE baz;
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DROP TABLE barbaz;
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