Thread: pgsql: The GiST scan algorithm uses LSNs to detect concurrent pages spl
pgsql: The GiST scan algorithm uses LSNs to detect concurrent pages spl
From
Heikki Linnakangas
Date:
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. Branch ------ REL8_1_STABLE Details ------- http://git.postgresql.org/gitweb?p=postgresql.git;a=commitdiff;h=acbffaa77d0c4846f8749daa45fde507be1e969b Modified Files -------------- src/backend/access/gist/gist.c | 10 ++++------ src/backend/access/gist/gistutil.c | 21 +++++++++++++++++++++ src/backend/access/gist/gistvacuum.c | 6 +++--- src/include/access/gist_private.h | 3 ++- 4 files changed, 30 insertions(+), 10 deletions(-)