Update xact.c comments for clarity.
This commit is contained in:
Bruce Momjian
parent
34529aeb64
commit
63e9734542
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@ -8,13 +8,13 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/access/transam/xact.c,v 1.137 2002/11/11 22:19:20 tgl Exp $
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* $Header: /cvsroot/pgsql/src/backend/access/transam/xact.c,v 1.138 2002/11/13 03:12:05 momjian 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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*
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* 1) system dies from some internal cause (Assert, etc..)
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* 2) user types abort
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* 1) system dies from some internal cause (syntax error, etc..)
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* 2) user types ABORT
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*
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* These two cases used to be treated identically, but now
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* we need to distinguish them. Why? consider the following
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@ -30,8 +30,8 @@
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* In case 1, we want to abort the transaction and return to the
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* default state. In case 2, there may be more commands coming
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* our way which are part of the same transaction block and we have
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* to ignore these commands until we see an END transaction.
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* (or an ABORT! --djm)
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* to ignore these commands until we see a COMMIT transaction or
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* ROLLBACK.
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*
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* Internal aborts are now handled by AbortTransactionBlock(), just as
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* they always have been, and user aborts are now handled by
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@ -52,14 +52,6 @@
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* TransactionCommandContext until this point.
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*
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* NOTES
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* This file is an attempt at a redesign of the upper layer
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* of the V1 transaction system which was too poorly thought
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* out to describe. This new system hopes to be both simpler
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* in design, simpler to extend and needs to contain added
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* functionality to solve problems beyond the scope of the V1
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* system. (In particuler, communication of transaction
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* information between parallel backends has to be supported)
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*
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* The essential aspects of the transaction system are:
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*
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* o transaction id generation
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@ -69,7 +61,7 @@
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* o lock cleanup
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*
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* Hence, the functional division of the transaction code is
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* based on what of the above things need to be done during
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* based on which of the above things need to be done during
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* a start/commit/abort transaction. For instance, the
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* routine AtCommit_Memory() takes care of all the memory
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* cleanup stuff done at commit time.
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@ -99,17 +91,17 @@
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* CommitTransactionBlock
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* AbortTransactionBlock
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*
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* These are invoked only in responce to a user "BEGIN", "END",
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* or "ABORT" command. The tricky part about these functions
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* These are invoked only in responce to a user "BEGIN WORK", "COMMIT",
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* or "ROLLBACK" command. The tricky part about these functions
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* is that they are called within the postgres main loop, in between
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* the StartTransactionCommand() and CommitTransactionCommand().
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*
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* For example, consider the following sequence of user commands:
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*
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* 1) begin
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* 2) retrieve (foo.all)
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* 3) append foo (bar = baz)
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* 4) end
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* 2) select * from foo
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* 3) insert into foo (bar = baz)
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* 4) commit
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*
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* in the main processing loop, this results in the following
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* transaction sequence:
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@ -120,15 +112,15 @@
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* \ CommitTransactionCommand();
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*
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* / StartTransactionCommand();
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* 2) < ProcessQuery(); << retrieve (foo.all)
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* 2) < ProcessQuery(); << select * from foo
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* \ CommitTransactionCommand();
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*
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* / StartTransactionCommand();
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* 3) < ProcessQuery(); << append foo (bar = baz)
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* 3) < ProcessQuery(); << insert into foo (bar = baz)
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* \ CommitTransactionCommand();
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*
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* / StartTransactionCommand();
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* 4) / ProcessUtility(); << end
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* 4) / ProcessUtility(); << commit
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* \ CommitTransactionBlock();
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* \ CommitTransactionCommand();
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*
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@ -139,19 +131,14 @@
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* outside these calls they need to do normal start/commit
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* processing.
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*
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* Furthermore, suppose the "retrieve (foo.all)" caused an abort
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* Furthermore, suppose the "select * from foo" caused an abort
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* condition. We would then want to abort the transaction and
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* ignore all subsequent commands up to the "end".
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* ignore all subsequent commands up to the "commit".
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* -cim 3/23/90
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*
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*-------------------------------------------------------------------------
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*/
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/*
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* Large object clean up added in CommitTransaction() to prevent buffer leaks.
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* [PA, 7/17/98]
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* [PA] is Pascal André <andre@via.ecp.fr>
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*/
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#include "postgres.h"
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#include <unistd.h>
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@ -201,9 +188,8 @@ static void CommitTransaction(void);
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static void RecordTransactionAbort(void);
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static void StartTransaction(void);
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/* ----------------
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* global variables holding the current transaction state.
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* ----------------
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/*
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* global variables holding the current transaction state.
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*/
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static TransactionStateData CurrentTransactionStateData = {
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0, /* transaction id */
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@ -211,13 +197,13 @@ static TransactionStateData CurrentTransactionStateData = {
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0, /* scan command id */
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0x0, /* start time */
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TRANS_DEFAULT, /* transaction state */
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TBLOCK_DEFAULT /* transaction block state */
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TBLOCK_DEFAULT /* transaction block state of client queries */
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};
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TransactionState CurrentTransactionState = &CurrentTransactionStateData;
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/*
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* User-tweakable parameters
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* User-tweakable parameters
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*/
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int DefaultXactIsoLevel = XACT_READ_COMMITTED;
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int XactIsoLevel;
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@ -236,22 +222,22 @@ static void *_RollbackData = NULL;
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/* ----------------------------------------------------------------
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* transaction state accessors
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* transaction state accessors
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* ----------------------------------------------------------------
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*/
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#ifdef NOT_USED
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/* --------------------------------
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* TransactionFlushEnabled()
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* SetTransactionFlushEnabled()
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* TransactionFlushEnabled()
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* SetTransactionFlushEnabled()
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*
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* These are used to test and set the "TransactionFlushState"
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* varable. If this variable is true (the default), then
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* the system will flush all dirty buffers to disk at the end
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* of each transaction. If false then we are assuming the
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* buffer pool resides in stable main memory, in which case we
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* only do writes as necessary.
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* These are used to test and set the "TransactionFlushState"
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* varable. If this variable is true (the default), then
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* the system will flush all dirty buffers to disk at the end
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* of each transaction. If false then we are assuming the
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* buffer pool resides in stable main memory, in which case we
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* only do writes as necessary.
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* --------------------------------
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*/
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static int TransactionFlushState = 1;
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@ -271,10 +257,10 @@ SetTransactionFlushEnabled(bool state)
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/* --------------------------------
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* IsTransactionState
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* IsTransactionState
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*
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* This returns true if we are currently running a query
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* within an executing transaction.
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* This returns true if we are currently running a query
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* within an executing transaction.
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* --------------------------------
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*/
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bool
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@ -303,10 +289,10 @@ IsTransactionState(void)
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}
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/* --------------------------------
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* IsAbortedTransactionBlockState
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* IsAbortedTransactionBlockState
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*
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* This returns true if we are currently running a query
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* within an aborted transaction block.
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* This returns true if we are currently running a query
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* within an aborted transaction block.
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* --------------------------------
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*/
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bool
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@ -322,7 +308,7 @@ IsAbortedTransactionBlockState(void)
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/* --------------------------------
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* GetCurrentTransactionId
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* GetCurrentTransactionId
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* --------------------------------
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*/
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TransactionId
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@ -335,7 +321,7 @@ GetCurrentTransactionId(void)
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/* --------------------------------
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* GetCurrentCommandId
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* GetCurrentCommandId
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* --------------------------------
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*/
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CommandId
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@ -348,7 +334,7 @@ GetCurrentCommandId(void)
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/* --------------------------------
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* GetCurrentTransactionStartTime
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* GetCurrentTransactionStartTime
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* --------------------------------
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*/
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AbsoluteTime
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@ -361,7 +347,7 @@ GetCurrentTransactionStartTime(void)
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/* --------------------------------
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* GetCurrentTransactionStartTimeUsec
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* GetCurrentTransactionStartTimeUsec
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* --------------------------------
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*/
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AbsoluteTime
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@ -376,12 +362,12 @@ GetCurrentTransactionStartTimeUsec(int *msec)
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/* --------------------------------
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* TransactionIdIsCurrentTransactionId
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* TransactionIdIsCurrentTransactionId
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*
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* During bootstrap, we cheat and say "it's not my transaction ID" even though
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* it is. Along with transam.c's cheat to say that the bootstrap XID is
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* already committed, this causes the tqual.c routines to see previously
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* inserted tuples as committed, which is what we need during bootstrap.
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* During bootstrap, we cheat and say "it's not my transaction ID" even though
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* it is. Along with transam.c's cheat to say that the bootstrap XID is
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* already committed, this causes the tqual.c routines to see previously
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* inserted tuples as committed, which is what we need during bootstrap.
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* --------------------------------
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*/
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bool
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@ -400,7 +386,7 @@ TransactionIdIsCurrentTransactionId(TransactionId xid)
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/* --------------------------------
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* CommandIdIsCurrentCommandId
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* CommandIdIsCurrentCommandId
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* --------------------------------
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*/
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bool
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@ -413,7 +399,7 @@ CommandIdIsCurrentCommandId(CommandId cid)
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/* --------------------------------
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* CommandCounterIncrement
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* CommandCounterIncrement
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* --------------------------------
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*/
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void
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@ -446,7 +432,7 @@ CommandCounterIncrement(void)
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*/
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/* --------------------------------
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* AtStart_Cache
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* AtStart_Cache
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* --------------------------------
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*/
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static void
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@ -471,7 +457,7 @@ AtStart_Locks(void)
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}
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/* --------------------------------
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* AtStart_Memory
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* AtStart_Memory
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* --------------------------------
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*/
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static void
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@ -512,7 +498,7 @@ AtStart_Memory(void)
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*/
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/*
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* RecordTransactionCommit
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* RecordTransactionCommit
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*/
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void
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RecordTransactionCommit(void)
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@ -620,7 +606,7 @@ RecordTransactionCommit(void)
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/* --------------------------------
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* AtCommit_Cache
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* AtCommit_Cache
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* --------------------------------
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*/
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static void
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@ -638,7 +624,7 @@ AtCommit_Cache(void)
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}
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/* --------------------------------
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* AtCommit_LocalCache
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* AtCommit_LocalCache
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* --------------------------------
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*/
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static void
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@ -651,7 +637,7 @@ AtCommit_LocalCache(void)
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}
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/* --------------------------------
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* AtCommit_Locks
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* AtCommit_Locks
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* --------------------------------
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*/
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static void
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@ -666,7 +652,7 @@ AtCommit_Locks(void)
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}
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/* --------------------------------
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* AtCommit_Memory
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* AtCommit_Memory
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* --------------------------------
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*/
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static void
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@ -694,7 +680,7 @@ AtCommit_Memory(void)
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*/
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/*
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* RecordTransactionAbort
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* RecordTransactionAbort
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*/
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static void
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RecordTransactionAbort(void)
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@ -763,7 +749,7 @@ RecordTransactionAbort(void)
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}
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/* --------------------------------
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* AtAbort_Cache
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* AtAbort_Cache
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* --------------------------------
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*/
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static void
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@ -774,7 +760,7 @@ AtAbort_Cache(void)
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}
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/* --------------------------------
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* AtAbort_Locks
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* AtAbort_Locks
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* --------------------------------
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*/
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static void
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@ -790,7 +776,7 @@ AtAbort_Locks(void)
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/* --------------------------------
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* AtAbort_Memory
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* AtAbort_Memory
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* --------------------------------
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*/
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static void
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@ -823,7 +809,7 @@ AtAbort_Memory(void)
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*/
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/* --------------------------------
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* AtCleanup_Memory
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* AtCleanup_Memory
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* --------------------------------
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*/
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static void
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@ -852,8 +838,7 @@ AtCleanup_Memory(void)
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*/
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/* --------------------------------
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* StartTransaction
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*
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* StartTransaction
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* --------------------------------
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*/
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static void
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@ -929,8 +914,7 @@ CurrentXactInProgress(void)
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#endif
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/* --------------------------------
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* CommitTransaction
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*
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* CommitTransaction
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* --------------------------------
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*/
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static void
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@ -1050,8 +1034,7 @@ CommitTransaction(void)
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}
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/* --------------------------------
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* AbortTransaction
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*
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* AbortTransaction
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* --------------------------------
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*/
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static void
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@ -1157,8 +1140,7 @@ AbortTransaction(void)
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}
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/* --------------------------------
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* CleanupTransaction
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*
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* CleanupTransaction
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* --------------------------------
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*/
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static void
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@ -1185,10 +1167,10 @@ CleanupTransaction(void)
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}
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/* --------------------------------
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* StartTransactionCommand
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* StartTransactionCommand
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*
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* preventChain, if true, forces autocommit behavior at the next
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* CommitTransactionCommand call.
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* preventChain, if true, forces autocommit behavior at the next
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* CommitTransactionCommand call.
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* --------------------------------
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*/
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void
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@ -1278,9 +1260,9 @@ StartTransactionCommand(bool preventChain)
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}
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/* --------------------------------
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* CommitTransactionCommand
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* CommitTransactionCommand
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*
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* forceCommit = true forces autocommit behavior even when autocommit is off.
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* forceCommit = true forces autocommit behavior even when autocommit is off.
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* --------------------------------
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*/
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void
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@ -1377,7 +1359,7 @@ CommitTransactionCommand(bool forceCommit)
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}
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/* --------------------------------
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* AbortCurrentTransaction
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* AbortCurrentTransaction
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* --------------------------------
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*/
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void
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@ -1454,22 +1436,22 @@ AbortCurrentTransaction(void)
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}
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/* --------------------------------
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* PreventTransactionChain
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* PreventTransactionChain
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*
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* This routine is to be called by statements that must not run inside
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* a transaction block, typically because they have non-rollback-able
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* side effects or do internal commits.
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* This routine is to be called by statements that must not run inside
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* a transaction block, typically because they have non-rollback-able
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* side effects or do internal commits.
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*
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* If we have already started a transaction block, issue an error; also issue
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* an error if we appear to be running inside a user-defined function (which
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* could issue more commands and possibly cause a failure after the statement
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* completes). In autocommit-off mode, we allow the statement if a block is
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* not already started, and force the statement to be autocommitted despite
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* the mode.
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* If we have already started a transaction block, issue an error; also issue
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* an error if we appear to be running inside a user-defined function (which
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* could issue more commands and possibly cause a failure after the statement
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* completes). In autocommit-off mode, we allow the statement if a block is
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* not already started, and force the statement to be autocommitted despite
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* the mode.
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*
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* stmtNode: pointer to parameter block for statement; this is used in
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* a very klugy way to determine whether we are inside a function.
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* stmtType: statement type name for error messages.
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* stmtNode: pointer to parameter block for statement; this is used in
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* a very klugy way to determine whether we are inside a function.
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* stmtType: statement type name for error messages.
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* --------------------------------
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*/
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void
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@ -1512,7 +1494,7 @@ PreventTransactionChain(void *stmtNode, const char *stmtType)
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* ----------------------------------------------------------------
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*/
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/* --------------------------------
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* BeginTransactionBlock
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* BeginTransactionBlock
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* --------------------------------
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*/
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void
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|
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@ -1546,7 +1528,7 @@ BeginTransactionBlock(void)
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}
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/* --------------------------------
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* EndTransactionBlock
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* EndTransactionBlock
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* --------------------------------
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*/
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void
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|
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@ -1594,7 +1576,7 @@ EndTransactionBlock(void)
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}
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/* --------------------------------
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* AbortTransactionBlock
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* AbortTransactionBlock
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* --------------------------------
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*/
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#ifdef NOT_USED
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|
@ -1632,7 +1614,7 @@ AbortTransactionBlock(void)
|
|||
#endif
|
||||
|
||||
/* --------------------------------
|
||||
* UserAbortTransactionBlock
|
||||
* UserAbortTransactionBlock
|
||||
* --------------------------------
|
||||
*/
|
||||
void
|
||||
|
|
@ -1678,11 +1660,11 @@ UserAbortTransactionBlock(void)
|
|||
}
|
||||
|
||||
/* --------------------------------
|
||||
* AbortOutOfAnyTransaction
|
||||
* AbortOutOfAnyTransaction
|
||||
*
|
||||
* This routine is provided for error recovery purposes. It aborts any
|
||||
* active transaction or transaction block, leaving the system in a known
|
||||
* idle state.
|
||||
* This routine is provided for error recovery purposes. It aborts any
|
||||
* active transaction or transaction block, leaving the system in a known
|
||||
* idle state.
|
||||
* --------------------------------
|
||||
*/
|
||||
void
|
||||
|
|
@ -1730,6 +1712,11 @@ IsTransactionBlock(void)
|
|||
return false;
|
||||
}
|
||||
|
||||
|
||||
/*
|
||||
* XLOG support routines
|
||||
*/
|
||||
|
||||
void
|
||||
xact_redo(XLogRecPtr lsn, XLogRecord *record)
|
||||
{
|
||||
|
|
|
|||
|
|
@ -7,7 +7,7 @@
|
|||
* Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
|
||||
* Portions Copyright (c) 1994, Regents of the University of California
|
||||
*
|
||||
* $Id: xact.h,v 1.46 2002/10/21 22:06:20 tgl Exp $
|
||||
* $Id: xact.h,v 1.47 2002/11/13 03:12:05 momjian Exp $
|
||||
*
|
||||
*-------------------------------------------------------------------------
|
||||
*/
|
||||
|
|
@ -46,9 +46,11 @@ typedef struct TransactionStateData
|
|||
|
||||
typedef TransactionStateData *TransactionState;
|
||||
|
||||
/* ----------------
|
||||
* transaction states
|
||||
* ----------------
|
||||
/*
|
||||
* transaction states - transaction state from server perspective
|
||||
*
|
||||
* Syntax error could cause transaction to abort, but client code thinks
|
||||
* it is still in a transaction, so we have to wait for COMMIT/ROLLBACK.
|
||||
*/
|
||||
#define TRANS_DEFAULT 0
|
||||
#define TRANS_START 1
|
||||
|
|
@ -56,9 +58,8 @@ typedef TransactionStateData *TransactionState;
|
|||
#define TRANS_COMMIT 3
|
||||
#define TRANS_ABORT 4
|
||||
|
||||
/* ----------------
|
||||
* transaction block states
|
||||
* ----------------
|
||||
/*
|
||||
* transaction block states - transaction state of client queries
|
||||
*/
|
||||
#define TBLOCK_DEFAULT 0
|
||||
#define TBLOCK_BEGIN 1
|
||||
|
|
|
|||
Loading…
Reference in New Issue