From b35711f5ef0941f79127acbec55a8ede5e27a5eb Mon Sep 17 00:00:00 2001 From: ChangAo Chen Date: Tue, 13 Aug 2024 11:45:07 +0800 Subject: [PATCH v4] Track transactions committed in BUILDING_SNAPSHOT. The historic snapshot previously didn't track transactions committed in BUILDING_SNAPSHOT, and this might result in a transaction taking an incorrect snapshot and logical decoding being interrupted. So we need track these transactions. We also need handle the xlog that marks a transaction as containing catalog changes in BUILDING_SNAPSHOT because the historic snapshot only tracks catalog modifying transactions. --- src/backend/replication/logical/decode.c | 45 +++++++++++++++++++++--- 1 file changed, 40 insertions(+), 5 deletions(-) diff --git a/src/backend/replication/logical/decode.c b/src/backend/replication/logical/decode.c index d687ceee33..6df558ad18 100644 --- a/src/backend/replication/logical/decode.c +++ b/src/backend/replication/logical/decode.c @@ -206,12 +206,16 @@ xact_decode(LogicalDecodingContext *ctx, XLogRecordBuffer *buf) uint8 info = XLogRecGetInfo(r) & XLOG_XACT_OPMASK; /* - * If the snapshot isn't yet fully built, we cannot decode anything, so - * bail out. + * If the snapshot hasn't started building yet, the transaction won't be + * decoded or tracked by the snapshot, so bail out. */ - if (SnapBuildCurrentState(builder) < SNAPBUILD_FULL_SNAPSHOT) + if (SnapBuildCurrentState(builder) < SNAPBUILD_BUILDING_SNAPSHOT) return; + /* + * Note that if the snapshot isn't yet fully built, the xlog is only used + * to build the snapshot and won't be decoded. + */ switch (info) { case XLOG_XACT_COMMIT: @@ -282,9 +286,11 @@ xact_decode(LogicalDecodingContext *ctx, XLogRecordBuffer *buf) { TransactionId xid; xl_xact_invals *invals; + bool has_snapshot; xid = XLogRecGetXid(r); invals = (xl_xact_invals *) XLogRecGetData(r); + has_snapshot = SnapBuildCurrentState(builder) >= SNAPBUILD_FULL_SNAPSHOT; /* * Execute the invalidations for xid-less transactions, @@ -293,7 +299,7 @@ xact_decode(LogicalDecodingContext *ctx, XLogRecordBuffer *buf) */ if (TransactionIdIsValid(xid)) { - if (!ctx->fast_forward) + if (!ctx->fast_forward && has_snapshot) ReorderBufferAddInvalidations(reorder, xid, buf->origptr, invals->nmsgs, @@ -301,7 +307,7 @@ xact_decode(LogicalDecodingContext *ctx, XLogRecordBuffer *buf) ReorderBufferXidSetCatalogChanges(ctx->reorder, xid, buf->origptr); } - else if (!ctx->fast_forward) + else if (!ctx->fast_forward && has_snapshot) ReorderBufferImmediateInvalidation(ctx->reorder, invals->nmsgs, invals->msgs); @@ -407,6 +413,8 @@ heap2_decode(LogicalDecodingContext *ctx, XLogRecordBuffer *buf) uint8 info = XLogRecGetInfo(buf->record) & XLOG_HEAP_OPMASK; TransactionId xid = XLogRecGetXid(buf->record); SnapBuild *builder = ctx->snapshot_builder; + /* True if the xlog marks the transaction as containing catalog changes */ + bool set_catalog_changes = (info == XLOG_HEAP2_NEW_CID); ReorderBufferProcessXid(ctx->reorder, xid, buf->origptr); @@ -416,7 +424,19 @@ heap2_decode(LogicalDecodingContext *ctx, XLogRecordBuffer *buf) */ if (SnapBuildCurrentState(builder) < SNAPBUILD_FULL_SNAPSHOT || ctx->fast_forward) + { + /* + * If the transaction contains catalog changes, we need mark it in + * reorder buffer before return as the snapshot only tracks catalog + * modifying transactions. The transaction before BUILDING_SNAPSHOT + * won't be tracked anyway(see SnapBuildCommitTxn), so skip it. + */ + if (set_catalog_changes && TransactionIdIsValid(xid) && + SnapBuildCurrentState(builder) >= SNAPBUILD_BUILDING_SNAPSHOT) + ReorderBufferXidSetCatalogChanges(ctx->reorder, xid, buf->origptr); + return; + } switch (info) { @@ -466,6 +486,8 @@ heap_decode(LogicalDecodingContext *ctx, XLogRecordBuffer *buf) uint8 info = XLogRecGetInfo(buf->record) & XLOG_HEAP_OPMASK; TransactionId xid = XLogRecGetXid(buf->record); SnapBuild *builder = ctx->snapshot_builder; + /* True if the xlog marks the transaction as containing catalog changes */ + bool set_catalog_changes = (info == XLOG_HEAP_INPLACE); ReorderBufferProcessXid(ctx->reorder, xid, buf->origptr); @@ -475,7 +497,19 @@ heap_decode(LogicalDecodingContext *ctx, XLogRecordBuffer *buf) */ if (SnapBuildCurrentState(builder) < SNAPBUILD_FULL_SNAPSHOT || ctx->fast_forward) + { + /* + * If the transaction contains catalog changes, we need mark it in + * reorder buffer before return as the snapshot only tracks catalog + * modifying transactions. The transaction before BUILDING_SNAPSHOT + * won't be tracked anyway(see SnapBuildCommitTxn), so skip it. + */ + if (set_catalog_changes && TransactionIdIsValid(xid) && + SnapBuildCurrentState(builder) >= SNAPBUILD_BUILDING_SNAPSHOT) + ReorderBufferXidSetCatalogChanges(ctx->reorder, xid, buf->origptr); + return; + } switch (info) { @@ -1301,6 +1335,7 @@ DecodeTXNNeedSkip(LogicalDecodingContext *ctx, XLogRecordBuffer *buf, Oid txn_dbid, RepOriginId origin_id) { if (SnapBuildXactNeedsSkip(ctx->snapshot_builder, buf->origptr) || + SnapBuildCurrentState(ctx->snapshot_builder) < SNAPBUILD_CONSISTENT || (txn_dbid != InvalidOid && txn_dbid != ctx->slot->data.database) || FilterByOrigin(ctx, origin_id)) return true; -- 2.34.1