postgres

Commit Graph

Author	SHA1	Message	Date
Tom Lane	282d2a03dd	HOT updates. When we update a tuple without changing any of its indexed columns, and the new version can be stored on the same heap page, we no longer generate extra index entries for the new version. Instead, index searches follow the HOT-chain links to ensure they find the correct tuple version. In addition, this patch introduces the ability to "prune" dead tuples on a per-page basis, without having to do a complete VACUUM pass to recover space. VACUUM is still needed to clean up dead index entries, however. Pavan Deolasee, with help from a bunch of other people.	19 years ago
Tom Lane	6889303531	Redefine the lp_flags field of item pointers as having four states, rather than two independent bits (one of which was never used in heap pages anyway, or at least hadn't been in a very long time). This gives us flexibility to add the HOT notions of redirected and dead item pointers without requiring anything so klugy as magic values of lp_off and lp_len. The state values are chosen so that for the states currently in use (pre-HOT) there is no change in the physical representation.	19 years ago
Tom Lane	85d72f0516	Teach heapam code to know the difference between a real seqscan and the pseudo HeapScanDesc created for a bitmap heap scan. This avoids some useless overhead during a bitmap scan startup, in particular invoking the syncscan code. (We might someday want to do that, but right now it's merely useless contention for shared memory, to say nothing of possibly pushing useful entries out of syncscan's small LRU list.) This also allows elimination of ugly pgstat_discount_heap_scan() kluge.	19 years ago
Tom Lane	77947c51c0	Fix up pgstats counting of live and dead tuples to recognize that committed and aborted transactions have different effects; also teach it not to assume that prepared transactions are always committed. Along the way, simplify the pgstats API by tying counting directly to Relations; I cannot detect any redeeming social value in having stats pointers in HeapScanDesc and IndexScanDesc structures. And fix a few corner cases in which counts might be missed because the relation's pgstat_info pointer hadn't been set.	19 years ago
Bruce Momjian	29dccf5fe0	Update CVS HEAD for 2007 copyright. Back branches are typically not back-stamped for this.	20 years ago
Tom Lane	68996463d4	Repair bug #2839 : the various ExecReScan functions need to reset ps_TupFromTlist in plan nodes that make use of it. This was being done correctly in join nodes and Result nodes but not in any relation-scan nodes. Bug would lead to bogus results if a set-returning function appeared in the targetlist of a subquery that could be rescanned after partial execution, for example a subquery within EXISTS(). Bug has been around forever :-( ... surprising it wasn't reported before.	20 years ago
Bruce Momjian	f99a569a2e	pgindent run for 8.2.	20 years ago
Bruce Momjian	e0522505bd	Remove 576 references of include files that were not needed.	20 years ago
Tom Lane	06e10abc0b	Fix problems with cached tuple descriptors disappearing while still in use by creating a reference-count mechanism, similar to what we did a long time ago for catcache entries. The back branches have an ugly solution involving lots of extra copies, but this way is more efficient. Reference counting is only applied to tupdescs that are actually in caches --- there seems no need to use it for tupdescs that are generated in the executor, since they'll go away during plan shutdown by virtue of being in the per-query memory context. Neil Conway and Tom Lane	20 years ago
Tom Lane	798e63ffb0	Remove CXT_printf/CXT1_printf macros. If anyone had found them to be of any use in the past many years, we'd have made some effort to include them in all executor node types; but in fact they were only in nodeAppend.c and nodeIndexscan.c, up until I copied nodeIndexscan.c's occurrence into the new bitmap node types. Remove some other unused macros in execdebug.h, too. Some day the whole header probably ought to go away in favor of better-designed facilities.	20 years ago
Bruce Momjian	f2f5b05655	Update copyright for 2006. Update scripts.	21 years ago
Tom Lane	2c0ef9777c	Extend the ExecInitNode API so that plan nodes receive a set of flag bits indicating which optional capabilities can actually be exercised at runtime. This will allow Sort and Material nodes, and perhaps later other nodes, to avoid unnecessary overhead in common cases. This commit just adds the infrastructure and arranges to pass the correct flag values down to plan nodes; none of the actual optimizations are here yet. I'm committing this separately in case anyone wants to measure the added overhead. (It should be negligible.) Simon Riggs and Tom Lane	21 years ago
Tom Lane	d780f07ac1	Adjust scan plan nodes to avoid getting an extra AccessShareLock on a relation if it's already been locked by execMain.c as either a result relation or a FOR UPDATE/SHARE relation. This avoids an extra trip to the shared lock manager state. Per my suggestion yesterday.	21 years ago
Tom Lane	de1dfc1209	Rearrange code in ExecInitBitmapHeapScan so that we don't initialize the child plan nodes until we have acquired lock on the relation to scan. The relative order of initialization of plan nodes isn't real important in other cases, but it's critical here because one is supposed to lock a relation before its indexes, not vice versa. The original coding was at least vulnerable to deadlock against DROP INDEX, and perhaps worse things.	21 years ago
Tom Lane	70f1482de3	Change seqscan logic so that we check visibility of all tuples on a page when we first read the page, rather than checking them one at a time. This allows us to take and release the buffer content lock just once per page, instead of once per tuple. Since it's a shared lock the contention penalty for holding the lock longer shouldn't be too bad. We can safely do this only when using an MVCC snapshot; else the assumption that visibility won't change over time is uncool. Therefore there are now two code paths depending on the snapshot type. I also made the same change in nodeBitmapHeapscan.c, where it can be done always because we only support MVCC snapshots for bitmap scans anyway. Also make some incidental cleanups in the APIs of these functions. Per a suggestion from Qingqing Zhou.	21 years ago
Tom Lane	dab52ab13d	Improve ExecStoreTuple to be smarter about replacing the contents of a TupleTableSlot: instead of calling ExecClearTuple, inline the needed operations, so that we can avoid redundant steps. In particular, when the old and new tuples are both on the same disk page, avoid releasing and re-acquiring the buffer pin --- this saves work in both the bufmgr and ResourceOwner modules. To make this improvement actually useful, partially revert a change I made on 2004-04-21 that caused SeqNext et al to call ExecClearTuple before ExecStoreTuple. The motivation for that, to avoid grabbing the BufMgrLock separately for releasing the old buffer and grabbing the new one, no longer applies. My profiling says that this saves about 5% of the CPU time for an all-in-memory seqscan.	21 years ago
Bruce Momjian	1dc3498251	Standard pgindent run for 8.1.	21 years ago
Tom Lane	cb8b6618ce	Revise pgstats stuff to fix the problems with not counting accesses generated by bitmap index scans. Along the way, simplify and speed up the code for counting sequential and index scans; it was both confusing and inefficient to be taking care of that in the per-tuple loops, IMHO. initdb forced because of internal changes in pg_stat view definitions.	21 years ago
Tom Lane	278bd0cc22	For some reason access/tupmacs.h has been #including utils/memutils.h, which is neither needed by nor related to that header. Remove the bogus inclusion and instead include the header in those C files that actually need it. Also fix unnecessary inclusions and bad inclusion order in tsearch2 files.	21 years ago
Tom Lane	4a8c5d0375	Create executor and planner-backend support for decoupled heap and index scans, using in-memory tuple ID bitmaps as the intermediary. The planner frontend (path creation and cost estimation) is not there yet, so none of this code can be executed. I have tested it using some hacked planner code that is far too ugly to see the light of day, however. Committing now so that the bulk of the infrastructure changes go in before the tree drifts under me.	21 years ago

20 Commits (b5d1608b0ae32e47ddfaf4c5e41afc7004171075)