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Commit102f464

Browse files
author
Nikita Glukhov
committed
WIP: TOAST iterators
1 parentd03a62e commit102f464

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12 files changed

+800
-18
lines changed

12 files changed

+800
-18
lines changed

‎src/backend/access/common/detoast.c

Lines changed: 105 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -312,6 +312,111 @@ detoast_attr_slice(struct varlena *attr,
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returnresult;
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}
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/* ----------
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* create_detoast_iterator -
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*
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* It only makes sense to initialize a de-TOAST iterator for external on-disk values.
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*
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* ----------
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*/
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DetoastIterator
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create_detoast_iterator(structvarlena*attr)
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{
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structvaratt_externaltoast_pointer;
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DetoastIteratoriter;
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if (VARATT_IS_EXTERNAL_ONDISK(attr))
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{
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iter= (DetoastIterator)palloc0(sizeof(DetoastIteratorData));
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iter->done= false;
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iter->nrefs=1;
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/* This is an externally stored datum --- initialize fetch datum iterator */
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iter->fetch_datum_iterator=create_fetch_datum_iterator(attr);
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VARATT_EXTERNAL_GET_POINTER(toast_pointer,attr);
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if (VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer))
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{
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iter->compressed= true;
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/* prepare buffer to received decompressed data */
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iter->buf=create_toast_buffer(toast_pointer.va_rawsize, false);
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/* initialize state for pglz_decompress_iterate() */
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iter->ctrl=0;
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iter->ctrlc=INVALID_CTRLC;
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}
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else
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{
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iter->compressed= false;
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/* point the buffer directly at the raw data */
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iter->buf=iter->fetch_datum_iterator->buf;
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}
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returniter;
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}
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elseif (VARATT_IS_EXTERNAL_INDIRECT(attr))
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{
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/* indirect pointer --- dereference it */
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structvaratt_indirectredirect;
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VARATT_EXTERNAL_GET_POINTER(redirect,attr);
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attr= (structvarlena*)redirect.pointer;
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/* nested indirect Datums aren't allowed */
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Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr));
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/* recurse in case value is still extended in some other way */
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returncreate_detoast_iterator(attr);
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}
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elseif (VARATT_IS_COMPRESSED(attr))
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{
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ToastBuffer*buf;
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iter= (DetoastIterator)palloc0(sizeof(DetoastIteratorData));
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iter->done= false;
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iter->nrefs=1;
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iter->fetch_datum_iterator=palloc0(sizeof(*iter->fetch_datum_iterator));
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iter->fetch_datum_iterator->buf=buf=create_toast_buffer(VARSIZE_ANY(attr), true);
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iter->fetch_datum_iterator->done= true;
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iter->compressed= true;
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memcpy((void*)buf->buf,attr,VARSIZE_ANY(attr));
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buf->limit= (char*)buf->capacity;
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/* prepare buffer to received decompressed data */
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iter->buf=create_toast_buffer(TOAST_COMPRESS_RAWSIZE(attr)+VARHDRSZ, false);
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/* initialize state for pglz_decompress_iterate() */
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iter->ctrl=0;
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iter->ctrlc=INVALID_CTRLC;
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returniter;
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}
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else
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/* in-line value -- no iteration used, even if it's compressed */
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returnNULL;
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}
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/* ----------
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* free_detoast_iterator -
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*
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* Free memory used by the de-TOAST iterator, including buffers and
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* fetch datum iterator.
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* ----------
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*/
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void
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free_detoast_iterator(DetoastIteratoriter)
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{
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if (iter==NULL)
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return;
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if (--iter->nrefs>0)
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return;
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if (iter->compressed)
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free_toast_buffer(iter->buf);
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free_fetch_datum_iterator(iter->fetch_datum_iterator);
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pfree(iter);
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}
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/* ----------
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* toast_fetch_datum -
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*

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