diff options
| author | Tomas Vondra | 2016-08-27 23:13:27 +0000 |
|---|---|---|
| committer | Pavan Deolasee | 2016-10-18 10:07:47 +0000 |
| commit | 2c7cb327f2424fb9acaf21e93614942e29c20c68 (patch) | |
| tree | 9597b929fc901d11335e15b21a46b0f63d3ad637 | |
| parent | b393122f4cb774b01dd2c0216ce074e3ba4ef567 (diff) | |
minor fixes in slot_deform_datarow - comment and attnum/natts rename
Added a comment explaining possible optimization when deforming
a DataRow message. Also renamed 'attnum' to 'natts' to more clearly
show the intent (attribute number vs. number of attributes).
| -rw-r--r-- | src/backend/access/common/heaptuple.c | 25 |
1 files changed, 16 insertions, 9 deletions
diff --git a/src/backend/access/common/heaptuple.c b/src/backend/access/common/heaptuple.c index 59296bfa1f..49c4988d6e 100644 --- a/src/backend/access/common/heaptuple.c +++ b/src/backend/access/common/heaptuple.c @@ -1201,13 +1201,21 @@ slot_deform_tuple(TupleTableSlot *slot, int natts) /* * slot_deform_datarow * Extract data from the DataRow message into Datum/isnull arrays. - * We always extract all atributes, as specified in tts_tupleDescriptor, - * because there is no easy way to find random attribute in the DataRow. + * + * We always extract all atributes, as specified in tts_tupleDescriptor, + * because there is no easy way to find random attribute in the DataRow. + * + * XXX There's an opportunity for optimization - we might extract only the + * attributes we already need (up to some attnum), and keep a pointer to + * the next byte in the DataRow message. On the next call we can either + * return immediately if the attnum is already extracted, or deform next + * chunk of the message. Not sure if this is worth the effort, as we're + * likely to extract all attributes from the message eventually. */ static void slot_deform_datarow(TupleTableSlot *slot) { - int attnum; + int natts; int i; int col_count; char *cur = slot->tts_datarow->msg; @@ -1219,17 +1227,17 @@ slot_deform_datarow(TupleTableSlot *slot) if (slot->tts_tupleDescriptor == NULL || slot->tts_datarow == NULL) return; - attnum = slot->tts_tupleDescriptor->natts; + natts = slot->tts_tupleDescriptor->natts; /* fastpath: exit if values already extracted */ - if (slot->tts_nvalid == attnum) + if (slot->tts_nvalid == natts) return; memcpy(&n16, cur, 2); cur += 2; col_count = ntohs(n16); - if (col_count != attnum) + if (col_count != natts) ereport(ERROR, (errcode(ERRCODE_DATA_CORRUPTED), errmsg("Tuple does not match the descriptor"))); @@ -1258,7 +1266,7 @@ slot_deform_datarow(TupleTableSlot *slot) } buffer = makeStringInfo(); - for (i = 0; i < attnum; i++) + for (i = 0; i < natts; i++) { Form_pg_attribute attr = slot->tts_tupleDescriptor->attrs[i]; int len; @@ -1327,8 +1335,7 @@ slot_deform_datarow(TupleTableSlot *slot) pfree(buffer->data); pfree(buffer); - slot->tts_nvalid = attnum; - + slot->tts_nvalid = natts; } /* |