On Wed, Nov 23, 2011 at 6:15 PM, Tom Lane <t...@sss.pgh.pa.us> wrote:
>> The real question is do we favour HOT cleanup on those small 8 tables, >> or do we favour HOT cleanup of every other table? > > No, the real question is why not think a little harder and see if we can > come up with a solution that doesn't involve making some cases worse to > make others better. Slightly modified patch attached. When we access a shared relation and the page is prunable we re-derive the cutoff value using GetOldestXmin. That code path is rarely taken. In particular, pg_shdepend is only accessed during object creation/alter/drop, so this isn't a path we can't spare a small amount little extra on, just like the trade-off we've taken to make locking faster for DML while making DDL a little slower. If this is still unacceptable, then I'll have to look at reducing impact on pg_shdepend from temp tables - which is still a plan. -- Simon Riggs http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services
fix_getsnapshotdata.v3.patch
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