diff options
Diffstat (limited to 'src/backend/access/transam/subtrans.c')
| -rw-r--r-- | src/backend/access/transam/subtrans.c | 17 |
1 files changed, 7 insertions, 10 deletions
diff --git a/src/backend/access/transam/subtrans.c b/src/backend/access/transam/subtrans.c index 8cdc9e0ab79..6a8e521f894 100644 --- a/src/backend/access/transam/subtrans.c +++ b/src/backend/access/transam/subtrans.c @@ -194,6 +194,7 @@ SUBTRANSShmemInit(void) SimpleLruInit(SubTransCtl, "Subtrans", NUM_SUBTRANS_BUFFERS, 0, SubtransSLRULock, "pg_subtrans", LWTRANCHE_SUBTRANS_BUFFER, SYNC_HANDLER_NONE); + SlruPagePrecedesUnitTests(SubTransCtl, SUBTRANS_XACTS_PER_PAGE); } /* @@ -354,13 +355,8 @@ TruncateSUBTRANS(TransactionId oldestXact) /* - * Decide which of two SUBTRANS page numbers is "older" for truncation purposes. - * - * We need to use comparison of TransactionIds here in order to do the right - * thing with wraparound XID arithmetic. However, if we are asked about - * page number zero, we don't want to hand InvalidTransactionId to - * TransactionIdPrecedes: it'll get weird about permanent xact IDs. So, - * offset both xids by FirstNormalTransactionId to avoid that. + * Decide whether a SUBTRANS page number is "older" for truncation purposes. + * Analogous to CLOGPagePrecedes(). */ static bool SubTransPagePrecedes(int page1, int page2) @@ -369,9 +365,10 @@ SubTransPagePrecedes(int page1, int page2) TransactionId xid2; xid1 = ((TransactionId) page1) * SUBTRANS_XACTS_PER_PAGE; - xid1 += FirstNormalTransactionId; + xid1 += FirstNormalTransactionId + 1; xid2 = ((TransactionId) page2) * SUBTRANS_XACTS_PER_PAGE; - xid2 += FirstNormalTransactionId; + xid2 += FirstNormalTransactionId + 1; - return TransactionIdPrecedes(xid1, xid2); + return (TransactionIdPrecedes(xid1, xid2) && + TransactionIdPrecedes(xid1, xid2 + SUBTRANS_XACTS_PER_PAGE - 1)); } |