While looking into a btree internal page using pg_filedump against an int4 index generated pgbench, I noticed that only item 2 has length 8, which indicates that the index tuple has only tuple header and has no index data. In my understanding this indicates that the item is used to represent a down link to a page. Question is, why the item is 2, not 1. I thought an index tuple indicating down link is always 1. Is this a sign that something goes wrong?
Block 3 ******************************************************** <Header> ----- Block Offset: 0x00006000 Offsets: Lower 1164 (0x048c) Block: Size 8192 Version 4 Upper 3624 (0x0e28) LSN: logid 2 recoff 0x1550a608 Special 8176 (0x1ff0) Items: 285 Free Space: 2460 Checksum: 0x0000 Prune XID: 0x00000000 Flags: 0x0000 () Length (including item array): 1164 <Data> ------ Item 1 -- Length: 16 Offset: 3624 (0x0e28) Flags: NORMAL Item 2 -- Length: 8 Offset: 8168 (0x1fe8) Flags: NORMAL Item 3 -- Length: 16 Offset: 8152 (0x1fd8) Flags: NORMAL Item 4 -- Length: 16 Offset: 8136 (0x1fc8) Flags: NORMAL Item 5 -- Length: 16 Offset: 8120 (0x1fb8) Flags: NORMAL [snip] Item 281 -- Length: 16 Offset: 3704 (0x0e78) Flags: NORMAL Item 282 -- Length: 16 Offset: 3688 (0x0e68) Flags: NORMAL Item 283 -- Length: 16 Offset: 3672 (0x0e58) Flags: NORMAL Item 284 -- Length: 16 Offset: 3656 (0x0e48) Flags: NORMAL Item 285 -- Length: 16 Offset: 3640 (0x0e38) Flags: NORMAL <Special Section> ----- BTree Index Section: Flags: 0x0000 () Blocks: Previous (0) Next (289) Level (1) CycleId (0) Best regards, -- Tatsuo Ishii SRA OSS, Inc. Japan English: http://www.sraoss.co.jp/index_en.php Japanese:http://www.sraoss.co.jp -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
