database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-09-02 04:21:28 +03:00
Code Activity

Prevent memory leaks associated with relcache rd_partcheck structures.

Browse Source 
The original coding of generate_partition_qual() just copied the list
of predicate expressions into the global CacheMemoryContext, making it
effectively impossible to clean up when the owning relcache entry is
destroyed --- the relevant code in RelationDestroyRelation() only managed
to free the topmost List header :-(.  This resulted in a session-lifespan
memory leak whenever a table partition's relcache entry is rebuilt.
Fortunately, that's not normally a large data structure, and rebuilds
shouldn't occur all that often in production situations; but this is
still a bug worth fixing back to v10 where the code was introduced.

To fix, put the cached expression tree into its own small memory context,
as we do with other complicated substructures of relcache entries.
Also, deal more honestly with the case that a partition has an empty
partcheck list; while that probably isn't a case that's very interesting
for production use, it's legal.

In passing, clarify comments about how partitioning-related relcache
data structures are managed, and add some Asserts that we're not leaking
old copies when we overwrite these data fields.

Amit Langote and Tom Lane

Discussion: https://postgr.es/m/7961.1552498252@sss.pgh.pa.us
This commit is contained in:
Tom Lane
2019-04-13 13:22:26 -04:00
parent c098509927
commit 5f1433ac5e
4 changed files with 75 additions and 28 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
src/include/utils/rel.h
View File

@@ -95,11 +95,13 @@ typedef struct RelationData
List *rd_fkeylist; /* list of ForeignKeyCacheInfo (see below) */
bool rd_fkeyvalid; /* true if list has been computed */
MemoryContext rd_partkeycxt; /* private memory cxt for the below */
struct PartitionKeyData *rd_partkey; /* partition key, or NULL */
MemoryContext rd_pdcxt; /* private context for partdesc */
MemoryContext rd_partkeycxt; /* private context for rd_partkey, if any */
struct PartitionDescData *rd_partdesc; /* partitions, or NULL */
MemoryContext rd_pdcxt; /* private context for rd_partdesc, if any */
List *rd_partcheck; /* partition CHECK quals */
bool rd_partcheckvalid; /* true if list has been computed */
MemoryContext rd_partcheckcxt; /* private cxt for rd_partcheck, if any */
/* data managed by RelationGetIndexList: */
List *rd_indexlist; /* list of OIDs of indexes on relation */