diff options
Diffstat (limited to 'src/backend/access/heap/heapam_handler.c')
| -rw-r--r-- | src/backend/access/heap/heapam_handler.c | 53 |
1 files changed, 53 insertions, 0 deletions
diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c index 8d8161fd971..56b2abda5fb 100644 --- a/src/backend/access/heap/heapam_handler.c +++ b/src/backend/access/heap/heapam_handler.c @@ -29,6 +29,7 @@ #include "access/rewriteheap.h" #include "access/tableam.h" #include "access/tsmapi.h" +#include "access/tuptoaster.h" #include "access/xact.h" #include "catalog/catalog.h" #include "catalog/index.h" @@ -2009,6 +2010,57 @@ heapam_relation_size(Relation rel, ForkNumber forkNumber) return nblocks * BLCKSZ; } +/* + * Check to see whether the table needs a TOAST table. It does only if + * (1) there are any toastable attributes, and (2) the maximum length + * of a tuple could exceed TOAST_TUPLE_THRESHOLD. (We don't want to + * create a toast table for something like "f1 varchar(20)".) + */ +static bool +heapam_relation_needs_toast_table(Relation rel) +{ + int32 data_length = 0; + bool maxlength_unknown = false; + bool has_toastable_attrs = false; + TupleDesc tupdesc = rel->rd_att; + int32 tuple_length; + int i; + + for (i = 0; i < tupdesc->natts; i++) + { + Form_pg_attribute att = TupleDescAttr(tupdesc, i); + + if (att->attisdropped) + continue; + data_length = att_align_nominal(data_length, att->attalign); + if (att->attlen > 0) + { + /* Fixed-length types are never toastable */ + data_length += att->attlen; + } + else + { + int32 maxlen = type_maximum_size(att->atttypid, + att->atttypmod); + + if (maxlen < 0) + maxlength_unknown = true; + else + data_length += maxlen; + if (att->attstorage != 'p') + has_toastable_attrs = true; + } + } + if (!has_toastable_attrs) + return false; /* nothing to toast? */ + if (maxlength_unknown) + return true; /* any unlimited-length attrs? */ + tuple_length = MAXALIGN(SizeofHeapTupleHeader + + BITMAPLEN(tupdesc->natts)) + + MAXALIGN(data_length); + return (tuple_length > TOAST_TUPLE_THRESHOLD); +} + /* ------------------------------------------------------------------------ * Planner related callbacks for the heap AM @@ -2592,6 +2644,7 @@ static const TableAmRoutine heapam_methods = { .index_validate_scan = heapam_index_validate_scan, .relation_size = heapam_relation_size, + .relation_needs_toast_table = heapam_relation_needs_toast_table, .relation_estimate_size = heapam_estimate_rel_size, |