diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/backend/utils/sort/logtape.c | 14 |
1 files changed, 10 insertions, 4 deletions
diff --git a/src/backend/utils/sort/logtape.c b/src/backend/utils/sort/logtape.c index 56ac0298c55..64ea237438b 100644 --- a/src/backend/utils/sort/logtape.c +++ b/src/backend/utils/sort/logtape.c @@ -537,14 +537,20 @@ ltsInitReadBuffer(LogicalTape *lt) * The tape set is initially empty. Use LogicalTapeCreate() to create * tapes in it. * - * Serial callers pass NULL argument for shared, and -1 for worker. Parallel - * worker callers pass a shared file handle and their own worker number. + * In a single-process sort, pass NULL argument for fileset, and -1 for + * worker. * - * Leader callers pass a shared file handle and -1 for worker. After creating - * the tape set, use LogicalTapeImport() to import the worker tapes into it. + * In a parallel sort, parallel workers pass the shared fileset handle and + * their own worker number. After the workers have finished, create the + * tape set in the leader, passing the shared fileset handle and -1 for + * worker, and use LogicalTapeImport() to import the worker tapes into it. * * Currently, the leader will only import worker tapes into the set, it does * not create tapes of its own, although in principle that should work. + * + * If preallocate is true, blocks for each individual tape are allocated in + * batches. This avoids fragmentation when writing multiple tapes at the + * same time. */ LogicalTapeSet * LogicalTapeSetCreate(bool preallocate, SharedFileSet *fileset, int worker) |