From 7ff02add837eb34354ca7197e521da3260aef9c1 Mon Sep 17 00:00:00 2001 From: Heikki Linnakangas Date: Tue, 16 Nov 2010 11:02:11 +0200 Subject: The GiST scan algorithm uses LSNs to detect concurrent pages splits, but temporary indexes are not WAL-logged. We used a constant LSN for temporary indexes, on the assumption that we don't need to worry about concurrent page splits in temporary indexes because they're only visible to the current session. But that assumption is wrong, it's possible to insert rows and split pages in the same session, while a scan is in progress. For example, by opening a cursor and fetching some rows, and INSERTing new rows before fetching some more. Fix by generating fake increasing LSNs, used in place of real LSNs in temporary GiST indexes. --- src/backend/access/gist/gist.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) (limited to 'src/backend/access/gist/gist.c') diff --git a/src/backend/access/gist/gist.c b/src/backend/access/gist/gist.c index 2742969c6af..405934caad1 100644 --- a/src/backend/access/gist/gist.c +++ b/src/backend/access/gist/gist.c @@ -22,8 +22,6 @@ #include "storage/indexfsm.h" #include "utils/memutils.h" -const XLogRecPtr XLogRecPtrForTemp = {1, 1}; - /* Working state for gistbuild and its callback */ typedef struct { @@ -132,7 +130,7 @@ gistbuild(PG_FUNCTION_ARGS) PageSetTLI(page, ThisTimeLineID); } else - PageSetLSN(page, XLogRecPtrForTemp); + PageSetLSN(page, GetXLogRecPtrForTemp()); UnlockReleaseBuffer(buffer); @@ -423,7 +421,7 @@ gistplacetopage(GISTInsertState *state, GISTSTATE *giststate) { for (ptr = dist; ptr; ptr = ptr->next) { - PageSetLSN(ptr->page, XLogRecPtrForTemp); + PageSetLSN(ptr->page, GetXLogRecPtrForTemp()); } } @@ -491,7 +489,7 @@ gistplacetopage(GISTInsertState *state, GISTSTATE *giststate) PageSetTLI(state->stack->page, ThisTimeLineID); } else - PageSetLSN(state->stack->page, XLogRecPtrForTemp); + PageSetLSN(state->stack->page, GetXLogRecPtrForTemp()); if (state->stack->blkno == GIST_ROOT_BLKNO) state->needInsertComplete = false; @@ -1027,7 +1025,7 @@ gistnewroot(Relation r, Buffer buffer, IndexTuple *itup, int len, ItemPointer ke PageSetTLI(page, ThisTimeLineID); } else - PageSetLSN(page, XLogRecPtrForTemp); + PageSetLSN(page, GetXLogRecPtrForTemp()); END_CRIT_SECTION(); } -- cgit v1.2.3