diff options
Diffstat (limited to 'src/backend')
| -rw-r--r-- | src/backend/utils/hash/dynahash.c | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/src/backend/utils/hash/dynahash.c b/src/backend/utils/hash/dynahash.c index 5948b01abc3..f4fbccdd7e4 100644 --- a/src/backend/utils/hash/dynahash.c +++ b/src/backend/utils/hash/dynahash.c @@ -1,7 +1,7 @@ /*------------------------------------------------------------------------- * * dynahash.c - * dynamic hash tables + * dynamic chained hash tables * * dynahash.c supports both local-to-a-backend hash tables and hash tables in * shared memory. For shared hash tables, it is the caller's responsibility @@ -41,6 +41,16 @@ * function must be supplied; comparison defaults to memcmp() and key copying * to memcpy() when a user-defined hashing function is selected. * + * Compared to simplehash, dynahash has the following benefits: + * + * - It supports partitioning, which is useful for shared memory access using + * locks. + * - Shared memory hashes are allocated in a fixed size area at startup and + * are discoverable by name from other processes. + * - Because entries don't need to be moved in the case of hash conflicts, has + * better performance for large entries + * - Guarantees stable pointers to entries. + * * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * |