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into a single mostly-physical-order scan of the index. This requires some ticklish interlocking considerations, but should create no material performance impact on normal index operations (at least given the already-committed changes to make scans work a page at a time). VACUUM itself should get significantly faster in any index that's degenerated to a very nonlinear page order. Also, we save one pass over the index entirely, except in the case where there were no deletions to do and so only one pass happened anyway. Original patch by Heikki Linnakangas, rework by Tom Lane. |
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| .. | ||
| ipc.c | ||
| ipci.c | ||
| Makefile | ||
| pmsignal.c | ||
| procarray.c | ||
| README | ||
| shmem.c | ||
| shmqueue.c | ||
| sinval.c | ||
| sinvaladt.c | ||
$PostgreSQL: pgsql/src/backend/storage/ipc/README,v 1.4 2003/11/29 19:51:56 pgsql Exp $ Mon Jul 18 11:09:22 PDT 1988 W.KLAS Cache invalidation synchronization routines: =========================================== The cache synchronization is done using a message queue. Every backend can register a message which then has to be read by all backends. A message read by all backends is removed from the queue automatically. If a message has been lost because the buffer was full, all backends that haven't read this message will be told that they have to reset their cache state. This is done at the time when they try to read the message queue. The message queue is implemented as a shared buffer segment. Actually, the queue is a circle to allow fast inserting, reading (invalidate data) and maintaining the buffer.