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Fix CREATE INDEX CONCURRENTLY for the newest prepared transactions.

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The purpose of commit 8a54e12a38 was to
fix this, and it sufficed when the PREPARE TRANSACTION completed before
the CIC looked for lock conflicts.  Otherwise, things still broke.  As
before, in a cluster having used CIC while having enabled prepared
transactions, queries that use the resulting index can silently fail to
find rows.  It may be necessary to reindex to recover from past
occurrences; REINDEX CONCURRENTLY suffices.  Fix this for future index
builds by making CIC wait for arbitrarily-recent prepared transactions
and for ordinary transactions that may yet PREPARE TRANSACTION.  As part
of that, have PREPARE TRANSACTION transfer locks to its dummy PGPROC
before it calls ProcArrayClearTransaction().  Back-patch to 9.6 (all
supported versions).

Andrey Borodin, reviewed (in earlier versions) by Andres Freund.

Discussion: https://postgr.es/m/01824242-AA92-4FE9-9BA7-AEBAFFEA3D0C@yandex-team.ru
This commit is contained in:
Noah Misch
2021-10-23 18:36:38 -07:00
parent fdd965d074
commit 3cd9c3b921
8 changed files with 362 additions and 36 deletions
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11
src/include/storage/lock.h
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@@ -47,10 +47,11 @@ extern bool Debug_deadlocks;
/*
* Top-level transactions are identified by VirtualTransactionIDs comprising
* PGPROC fields backendId and lxid. For prepared transactions, the
* LocalTransactionId is an ordinary XID. These are guaranteed unique over
* the short term, but will be reused after a database restart or XID
* wraparound; hence they should never be stored on disk.
* PGPROC fields backendId and lxid. For recovered prepared transactions, the
* LocalTransactionId is an ordinary XID; LOCKTAG_VIRTUALTRANSACTION never
* refers to that kind. These are guaranteed unique over the short term, but
* will be reused after a database restart or XID wraparound; hence they
* should never be stored on disk.
*
* Note that struct VirtualTransactionId can not be assumed to be atomically
* assignable as a whole. However, type LocalTransactionId is assumed to
@@ -70,7 +71,7 @@ typedef struct
#define LocalTransactionIdIsValid(lxid) ((lxid) != InvalidLocalTransactionId)
#define VirtualTransactionIdIsValid(vxid) \
(LocalTransactionIdIsValid((vxid).localTransactionId))
#define VirtualTransactionIdIsPreparedXact(vxid) \
#define VirtualTransactionIdIsRecoveredPreparedXact(vxid) \
((vxid).backendId == InvalidBackendId)
#define VirtualTransactionIdEquals(vxid1, vxid2) \
((vxid1).backendId == (vxid2).backendId && \