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PostgrreSQl heap decode refactoring
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Pavel Safonov committed Jul 29, 2022
1 parent ce9ae76 commit 01b380e
Showing 1 changed file with 188 additions and 158 deletions.
346 changes: 188 additions & 158 deletions format/postgres/flavours/postgres14/pgheap.go
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Original file line number Diff line number Diff line change
Expand Up @@ -90,7 +90,9 @@ type heapPageD struct {
pdSpecial uint16
pd_pagesize_version uint16

itemIds []itemIdDataD
itemIds []itemIdDataD
pagePosBegin uint64
itemsEnd int64
}

func (hp *heapPageD) getItemId(offset uint32) (bool, itemIdDataD) {
Expand Down Expand Up @@ -137,161 +139,189 @@ func decodeHeapPages(d *decode.D) {
page := &heapPageD{}
heap.page = page

pagePosBegin := common.RoundDown(heap.pageSize, uint64(d.Pos()/8))

d.FieldStruct("HeapPage", func(d *decode.D) {
/* 0 | 8 */ // PageXLogRecPtr pd_lsn;
/* 8 | 2 */ // uint16 pd_checksum;
/* 10 | 2 */ // uint16 pd_flags;
/* 12 | 2 */ // LocationIndex pd_lower;
/* 14 | 2 */ // LocationIndex pd_upper;
/* 16 | 2 */ // LocationIndex pd_special;
/* 18 | 2 */ // uint16 pd_pagesize_version;
/* 20 | 4 */ // TransactionId pd_prune_xid;
/* 24 | 0 */ // ItemIdData pd_linp[];
d.FieldStruct("PageHeaderData", func(d *decode.D) {
d.FieldStruct("pd_lsn", func(d *decode.D) {
/* 0 | 4 */ // uint32 xlogid;
/* 4 | 4 */ // uint32 xrecoff;
d.FieldU32("xlogid", common.HexMapper)
d.FieldU32("xrecoff", common.HexMapper)
})
d.FieldU16("pd_checksum")
d.FieldU16("pd_flags")
page.pdLower = uint16(d.FieldU16("pd_lower"))
page.pdUpper = uint16(d.FieldU16("pd_upper"))
page.pdSpecial = uint16(d.FieldU16("pd_special"))
page.pd_pagesize_version = uint16(d.FieldU16("pd_pagesize_version"))
d.FieldU32("pd_prune_xid")

// ItemIdData pd_linp[];
itemsEnd := int64(pagePosBegin*8) + int64(page.pdLower*8)
d.FieldArray("pd_linp", func(d *decode.D) {
for {
checkPos := d.Pos()
if checkPos >= itemsEnd {
break
}
/* 0: 0 | 4 */ // unsigned int lp_off: 15
/* 1: 7 | 4 */ // unsigned int lp_flags: 2
/* 2: 1 | 4 */ // unsigned int lp_len: 15
d.FieldStruct("ItemIdData", func(d *decode.D) {
itemId := itemIdDataD{}

itemPos := d.Pos()
itemId.lpOff = uint32(d.FieldU32("lp_off", common.LpOffMapper))
d.SeekAbs(itemPos)
itemId.lpFlags = uint32(d.FieldU32("lp_flags", common.LpFlagsMapper))
d.SeekAbs(itemPos)
itemId.lpLen = uint32(d.FieldU32("lp_len", common.LpLenMapper))

page.itemIds = append(page.itemIds, itemId)
})
} // for pd_linp
}) // pd_linp in PageHeaderData

}) // PageHeaderData, PageHeader

// free space
freeSpaceEnd := int64(pagePosBegin*8) + int64(page.pdUpper*8)
freeSpaceNBits := freeSpaceEnd - d.Pos()
d.FieldRawLen("FreeSpace", freeSpaceNBits, scalar.RawHex)

// Tuples
d.FieldArray("Tuples", func(d *decode.D) {
for i := 0; i < len(page.itemIds); i++ {
id := page.itemIds[i]
if id.lpOff == 0 || id.lpLen == 0 {
continue
}

pos := int64(pagePosBegin)*8 + int64(page.itemIds[i].lpOff)*8
tupleDataLen := id.lpLen - SizeOfHeapTupleHeaderData

d.SeekAbs(pos)

/* 0 | 12 */ // union {
/* 12 */ // HeapTupleFields t_heap;
/* 12 */ // DatumTupleFields t_datum;
// } t_choice;
/* total size (bytes): 12 */
/*
/* 12 | 6 */ // ItemPointerData t_ctid;
/* 18 | 2 */ // uint16 t_infomask2;
/* 20 | 2 */ // uint16 t_infomask;
/* 22 | 1 */ // uint8 t_hoff;
/* 23 | 0 */ // bits8 t_bits[];
/* XXX 1-byte padding */
//
/* total size (bytes): 24 */
d.FieldStruct("HeapTupleHeaderData", func(d *decode.D) {
d.FieldStruct("t_choice", func(d *decode.D) {
pos1 := d.Pos()
// type = struct HeapTupleFields {
/* 0 | 4 */ // TransactionId t_xmin;
/* 4 | 4 */ // TransactionId t_xmax;
/* 8 | 4 */ // union {
/* 4 */ // CommandId t_cid;
/* 4 */ // TransactionId t_xvac;
// } t_field3;
/* total size (bytes): 4 */
//
/* total size (bytes): 12 */
d.FieldStruct("t_heap", func(d *decode.D) {
d.FieldU32("t_xmin")
d.FieldU32("t_xmax")
d.FieldStruct("t_field3", func(d *decode.D) {
pos2 := d.Pos()
d.FieldU32("t_cid")
d.SeekAbs(pos2)
d.FieldU32("t_xvac")
}) // t_field3
}) // HeapTupleFields t_heap

d.SeekAbs(pos1)
// type = struct DatumTupleFields {
/* 0 | 4 */ // int32 datum_len_;
/* 4 | 4 */ // int32 datum_typmod;
/* 8 | 4 */ // Oid datum_typeid;
//
/* total size (bytes): 12 */

// t_datum
d.FieldStruct("t_datum", func(d *decode.D) {
d.FieldS32("datum_len_")
d.FieldS32("datum_typmod")
d.FieldU32("datum_typeid")
}) // DatumTupleFields t_datum
}) // t_choice

d.FieldStruct("t_ctid", func(d *decode.D) {
/* 0 | 4 */ // BlockIdData ip_blkid;
/* 4 | 2 */ // OffsetNumber ip_posid;
d.FieldU32("ip_blkid")
d.FieldU16("ip_posid")
}) // ItemPointerData t_ctid

/* 18 | 2 */ // uint16 t_infomask2;
/* 20 | 2 */ // uint16 t_infomask;
/* 22 | 1 */ // uint8 t_hoff;
/* 23 | 0 */ // bits8 t_bits[];
/* XXX 1-byte padding */
d.FieldU16("t_infomask2")
d.FieldU16("t_infomask")
d.FieldU8("t_hoff")
d.U8()

d.FieldRawLen("t_bits", int64(tupleDataLen*8), scalar.RawHex)

}) // HeapTupleHeaderData
}
}) // Tuples

// end of page
endLen := uint64(d.Pos() / 8)
pageEnd := common.TypeAlign(heap.pageSize, endLen)
d.SeekAbs(int64(pageEnd) * 8)
}) // HeapPage

} // for Heap pages
d.FieldStruct("HeapPage", decodeHeapPage)

// end of page
endLen := uint64(d.Pos() / 8)
pageEnd := common.TypeAlign(heap.pageSize, endLen)
d.SeekAbs(int64(pageEnd) * 8)
}
}

func decodeHeapPage(d *decode.D) {
heap := getHeapD(d)

page := &heapPageD{}
heap.page = page

pagePosBegin := common.RoundDown(heap.pageSize, uint64(d.Pos()/8))
page.pagePosBegin = pagePosBegin

// PageHeader
d.FieldStruct("PageHeaderData", decodePageHeaderData)

// free space
freeSpaceEnd := int64(pagePosBegin*8) + int64(page.pdUpper*8)
freeSpaceNBits := freeSpaceEnd - d.Pos()
d.FieldRawLen("FreeSpace", freeSpaceNBits, scalar.RawHex)

// Tuples
d.FieldArray("Tuples", decodeTuples)
}

/* 0 | 8 */ // PageXLogRecPtr pd_lsn;
/* 8 | 2 */ // uint16 pd_checksum;
/* 10 | 2 */ // uint16 pd_flags;
/* 12 | 2 */ // LocationIndex pd_lower;
/* 14 | 2 */ // LocationIndex pd_upper;
/* 16 | 2 */ // LocationIndex pd_special;
/* 18 | 2 */ // uint16 pd_pagesize_version;
/* 20 | 4 */ // TransactionId pd_prune_xid;
/* 24 | 0 */ // ItemIdData pd_linp[];
func decodePageHeaderData(d *decode.D) {
heap := getHeapD(d)
page := heap.page

d.FieldStruct("pd_lsn", func(d *decode.D) {
/* 0 | 4 */ // uint32 xlogid;
/* 4 | 4 */ // uint32 xrecoff;
d.FieldU32("xlogid", common.HexMapper)
d.FieldU32("xrecoff", common.HexMapper)
})
d.FieldU16("pd_checksum")
d.FieldU16("pd_flags")
page.pdLower = uint16(d.FieldU16("pd_lower"))
page.pdUpper = uint16(d.FieldU16("pd_upper"))
page.pdSpecial = uint16(d.FieldU16("pd_special"))
page.pd_pagesize_version = uint16(d.FieldU16("pd_pagesize_version"))
d.FieldU32("pd_prune_xid")

// ItemIdData pd_linp[];
page.itemsEnd = int64(page.pagePosBegin*8) + int64(page.pdLower*8)
d.FieldArray("pd_linp", decodeItemIds)
}

func decodeItemIds(d *decode.D) {
heap := getHeapD(d)
page := heap.page

for {
checkPos := d.Pos()
if checkPos >= page.itemsEnd {
break
}
/* 0: 0 | 4 */ // unsigned int lp_off: 15
/* 1: 7 | 4 */ // unsigned int lp_flags: 2
/* 2: 1 | 4 */ // unsigned int lp_len: 15
d.FieldStruct("ItemIdData", func(d *decode.D) {
itemId := itemIdDataD{}

itemPos := d.Pos()
itemId.lpOff = uint32(d.FieldU32("lp_off", common.LpOffMapper))
d.SeekAbs(itemPos)
itemId.lpFlags = uint32(d.FieldU32("lp_flags", common.LpFlagsMapper))
d.SeekAbs(itemPos)
itemId.lpLen = uint32(d.FieldU32("lp_len", common.LpLenMapper))

page.itemIds = append(page.itemIds, itemId)
})
} // for pd_linp
}

func decodeTuples(d *decode.D) {
heap := getHeapD(d)
page := heap.page

for i := 0; i < len(page.itemIds); i++ {
id := page.itemIds[i]
if id.lpOff == 0 || id.lpLen == 0 {
continue
}

pos := int64(page.pagePosBegin)*8 + int64(page.itemIds[i].lpOff)*8
tupleDataLen := id.lpLen - SizeOfHeapTupleHeaderData

// seek to tuple with ItemId offset
d.SeekAbs(pos)

/* 0 | 12 */ // union {
/* 12 */ // HeapTupleFields t_heap;
/* 12 */ // DatumTupleFields t_datum;
// } t_choice;
/* total size (bytes): 12 */
/*
/* 12 | 6 */ // ItemPointerData t_ctid;
/* 18 | 2 */ // uint16 t_infomask2;
/* 20 | 2 */ // uint16 t_infomask;
/* 22 | 1 */ // uint8 t_hoff;
/* 23 | 0 */ // bits8 t_bits[];
/* XXX 1-byte padding */
//
/* total size (bytes): 24 */
d.FieldStruct("HeapTupleHeaderData", func(d *decode.D) {
d.FieldStruct("t_choice", decodeTChoice)

d.FieldStruct("t_ctid", func(d *decode.D) {
/* 0 | 4 */ // BlockIdData ip_blkid;
/* 4 | 2 */ // OffsetNumber ip_posid;
d.FieldU32("ip_blkid")
d.FieldU16("ip_posid")
}) // ItemPointerData t_ctid

/* 18 | 2 */ // uint16 t_infomask2;
/* 20 | 2 */ // uint16 t_infomask;
/* 22 | 1 */ // uint8 t_hoff;
/* 23 | 0 */ // bits8 t_bits[];
/* XXX 1-byte padding */
d.FieldU16("t_infomask2")
d.FieldU16("t_infomask")
d.FieldU8("t_hoff")
d.U8()

d.FieldRawLen("t_bits", int64(tupleDataLen*8), scalar.RawHex)

}) // HeapTupleHeaderData
} // for ItemsIds
}

/* 0 | 12 */ // union {
/* 12 */ // HeapTupleFields t_heap;
/* 12 */ // DatumTupleFields t_datum;
// } t_choice;
func decodeTChoice(d *decode.D) {
pos1 := d.Pos()
// type = struct HeapTupleFields {
/* 0 | 4 */ // TransactionId t_xmin;
/* 4 | 4 */ // TransactionId t_xmax;
/* 8 | 4 */ // union {
/* 4 */ // CommandId t_cid;
/* 4 */ // TransactionId t_xvac;
// } t_field3;
/* total size (bytes): 4 */
//
/* total size (bytes): 12 */
d.FieldStruct("t_heap", func(d *decode.D) {
d.FieldU32("t_xmin")
d.FieldU32("t_xmax")
d.FieldStruct("t_field3", func(d *decode.D) {
pos2 := d.Pos()
d.FieldU32("t_cid")
d.SeekAbs(pos2)
d.FieldU32("t_xvac")
}) // t_field3
}) // HeapTupleFields t_heap

// restore position for union
d.SeekAbs(pos1)
// type = struct DatumTupleFields {
/* 0 | 4 */ // int32 datum_len_;
/* 4 | 4 */ // int32 datum_typmod;
/* 8 | 4 */ // Oid datum_typeid;
//
/* total size (bytes): 12 */
d.FieldStruct("t_datum", func(d *decode.D) {
d.FieldS32("datum_len_")
d.FieldS32("datum_typmod")
d.FieldU32("datum_typeid")
}) // DatumTupleFields t_datum
}

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