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Update outdated comments in nodeAgg.c.

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Author: Zhang Mingli
Reviewed-by: Richard Guo
Discussion: https://postgr.es/m/198a8d1e-0792-4e7f-828e-902aa342f36e@Spark
This commit is contained in:
Jeff Davis
2025-02-18 10:28:05 -08:00
parent c623e8593e
commit a1f7f80bfe
1 changed files with 2 additions and 4 deletions
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6
src/backend/executor/nodeAgg.c
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@ -1454,7 +1454,7 @@ find_cols_walker(Node *node, FindColsContext *context)
* To implement hashed aggregation, we need a hashtable that stores a
* representative tuple and an array of AggStatePerGroup structs for each
* distinct set of GROUP BY column values. We compute the hash key from the
* GROUP BY columns. The per-group data is allocated in lookup_hash_entry(),
* GROUP BY columns. The per-group data is allocated in initialize_hash_entry(),
* for each entry.
*
* We have a separate hashtable and associated perhash data structure for each
@ -1551,7 +1551,7 @@ build_hash_table(AggState *aggstate, int setno, long nbuckets)
* at all. Only columns of the first two types need to be stored in the
* hashtable, and getting rid of the others can make the table entries
* significantly smaller. The hashtable only contains the relevant columns,
* and is packed/unpacked in lookup_hash_entry() / agg_retrieve_hash_table()
* and is packed/unpacked in lookup_hash_entries() / agg_retrieve_hash_table()
* into the format of the normal input descriptor.
*
* Additional columns, in addition to the columns grouped by, come from two
@ -2102,8 +2102,6 @@ initialize_hash_entry(AggState *aggstate, TupleHashTable hashtable,
/*
* Look up hash entries for the current tuple in all hashed grouping sets.
*
* Be aware that lookup_hash_entry can reset the tmpcontext.
*
* Some entries may be left NULL if we are in "spill mode". The same tuple
* will belong to different groups for each grouping set, so may match a group
* already in memory for one set and match a group not in memory for another