Skip to content

Commit

Permalink
Document tts_orioledb_getsomeattrs()
Browse files Browse the repository at this point in the history
  • Loading branch information
@akorotkov
akorotkov committed Jun 30, 2024
1 parent fef57e6 commit 4914dba
Showing 1 changed file with 72 additions and 7 deletions.
79 changes: 72 additions & 7 deletions src/tuple/slot.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -166,63 +166,108 @@ alloc_to_toast_vfree_detoasted(TupleTableSlot *slot)
}

/*
* Attribute values are readily available in tts_values and tts_isnull array
* in a OTableSlot. So there should be no need to call either of the
* following two functions.
* This function is designed to populate the attributes of a tuple table slot
* from an OrioleDB tuple. It selectively retrieves attributes based on
* the provided number of attributes (__natts) and updates the slot's values
* and null flags accordingly.
*/
static void
tts_orioledb_getsomeattrs(TupleTableSlot *slot, int __natts)
{
/*
* Cast the generic TupleTableSlot to an OTableSlot for OrioleDB specific
* operations.
*/
OTableSlot *oslot = (OTableSlot *) slot;

/* Declaration of variables used throughout the function. */
int natts,
attnum,
ctid_off,
res_ctidoff;
OTableDescr *descr = oslot->descr;
Datum *values = slot->tts_values;
bool *isnull = slot->tts_isnull;
bool hastoast = false;
OTableDescr *descr = oslot->descr; /* Descriptor for the table. */
Datum *values = slot->tts_values; /* Array to store attribute
* values. */
bool *isnull = slot->tts_isnull; /* Array to store null flags for
* attributes. */
bool hastoast = false; /* Flag to indicate presence of TOASTed
* attributes. */
OIndexDescr *idx;
bool index_order;
int cur_tbl_attnum = 0;

/*
* Early return if the requested number of attributes is already valid or
* the tuple is null.
*/
if (__natts <= slot->tts_nvalid || O_TUPLE_IS_NULL(oslot->tuple))
return;

/* Ensure the descriptor is not NULL. */
Assert(descr);
idx = descr->indices[oslot->ixnum];

/* Determine if the attributes should be fetched in index order. */
index_order = slot->tts_tupleDescriptor->tdtypeid == RECORDOID;
if (oslot->ixnum == PrimaryIndexNumber)
index_order = index_order &&
slot->tts_tupleDescriptor->natts == idx->nFields;

/*
* Ensure that if there are valid attributes, the slot is for the primary
* index.
*/
Assert(slot->tts_nvalid == 0 || oslot->ixnum == PrimaryIndexNumber);

/*
* Determine the offset of the attributes due to the possible presence of
* ctid column.
*/
if (GET_PRIMARY(descr)->primaryIsCtid && oslot->ixnum == PrimaryIndexNumber)
ctid_off = 1;
else
ctid_off = 0;

res_ctidoff = GET_PRIMARY(descr)->primaryIsCtid ? 1 : 0;

/*
* Determine the number of attributes to process based on the index type
* and the order of attributes.
*/
if (oslot->ixnum == PrimaryIndexNumber && oslot->leafTuple)
{
if (index_order)
{
/*
* The attributes are stored in the index order. So fetch all the
* attributes at once.
*/
natts = descr->tupdesc->natts;
}
else
{
natts = Min(__natts, descr->tupdesc->natts);
}
}
else
{
/*
* For secondary indexes, the attributes are also stored in the index
* order. So fetch all the attributes at once.
*/
natts = oslot->state.desc->natts;
}

/* Iterate over the attributes to populate values and null flags. */
for (attnum = slot->tts_nvalid; attnum < natts; attnum++)
{
Form_pg_attribute thisatt;
int res_attnum;

/*
* Determine the result attribute number based on the index type and
* the order of attributes.
*/
if (oslot->ixnum == PrimaryIndexNumber)
{
if (index_order)
Expand Down Expand Up @@ -251,17 +296,27 @@ tts_orioledb_getsomeattrs(TupleTableSlot *slot, int __natts)
res_attnum = idx->fields[attnum].tableAttnum - 1;
}

/* Ensure the result attribute number is valid. */
Assert(res_attnum >= -2);
if (res_attnum >= 0)
{
/*
* Read the next field value and update the slot's value and null
* arrays.
*/
values[res_attnum] = o_tuple_read_next_field(&oslot->state,
&isnull[res_attnum]);

/* Determine the attribute metadata based on the index and order. */
if (oslot->ixnum == PrimaryIndexNumber && !index_order)
thisatt = TupleDescAttr(slot->tts_tupleDescriptor, attnum);
else
thisatt = TupleDescAttr(idx->leafTupdesc, attnum);

/*
* Check for TOASTed attributes and adjust the number of
* attributes if necessary.
*/
if (!isnull[res_attnum] && !thisatt->attbyval && thisatt->attlen < 0)
{
Pointer p = DatumGetPointer(values[res_attnum]);
Expand All @@ -277,6 +332,7 @@ tts_orioledb_getsomeattrs(TupleTableSlot *slot, int __natts)
}
else if (res_attnum == -1)
{
/* Special handling for ctid attribute. */
Datum iptr_value PG_USED_FOR_ASSERTS_ONLY;
bool iptr_null;

Expand All @@ -289,23 +345,28 @@ tts_orioledb_getsomeattrs(TupleTableSlot *slot, int __natts)
}
else if (res_attnum == -2)
{
/* Handle dropped attributes by reading and ignoring the value. */
bool dropped_null;

(void) o_tuple_read_next_field(&oslot->state, &dropped_null);
}
}

/* Process TOASTed attributes if any were found. */
if (hastoast)
{
OTuple pkey;

Assert(oslot->ixnum == PrimaryIndexNumber);

/* Allocate memory for TOASTed attributes if not already done. */
if (!oslot->to_toast)
alloc_to_toast_vfree_detoasted(slot);

/* Generate a primary key for the TOASTed attributes. */
pkey = tts_orioledb_make_key(slot, descr);

/* Iterate over attributes to process TOASTed values. */
for (attnum = 0; attnum < natts; attnum++)
{
Form_pg_attribute thisatt;
Expand All @@ -317,6 +378,7 @@ tts_orioledb_getsomeattrs(TupleTableSlot *slot, int __natts)

if (IS_TOAST_POINTER(p))
{
/* Replace TOASTed value with a detoasted version. */
MemoryContext mcxt = MemoryContextSwitchTo(slot->tts_mcxt);
OToastValue toastValue;

Expand All @@ -330,11 +392,14 @@ tts_orioledb_getsomeattrs(TupleTableSlot *slot, int __natts)
}
}
}
/* Free the primary key memory. */
pfree(pkey.data);
}

/* Ensure the number of processed attributes matches the expected count. */
Assert(attnum == natts);

/* Update the slot's valid attribute count. */
slot->tts_nvalid = natts;
}

Expand Down

0 comments on commit 4914dba

Please sign in to comment.