Details
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Bug
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Status: Closed (View Workflow)
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Critical
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Resolution: Fixed
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10.5.2, 10.6.0, 10.5, 10.6, 10.7, 10.8, 10.9, 10.10
Description
mleich provided rr replay traces where mariadb-backup --prepare fails like this:
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10.6 92032499874259bae7455130958ea7f38c4d53a3 |
2022-08-31 9:06:55 0 [Note] InnoDB: Starting final batch to recover 241 pages from redo log.
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2022-08-31 9:06:58 0 [ERROR] InnoDB: OPT_PAGE_CHECKSUM mismatch on [page id: space=0, page number=514]
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2022-08-31 9:06:58 0 [ERROR] InnoDB: Set innodb_force_recovery=1 to ignore corruption.
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2022-08-31 9:06:58 0 [ERROR] InnoDB: Unable to apply log to corrupted page [page id: space=0, page number=514]; set innodb_force_recovery to ignore
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2022-08-31 9:06:58 0 [ERROR] InnoDB: Plugin initialization aborted at srv0start.cc[1490] with error Data structure corruption
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I extracted a copy of the page both from the backup and from the server at the logical point of time when the OPT_PAGE_CHECKSUM record was written. Apart from FIL_PAGE_LSN which is excluded from the checksum, the pages differ as follows:
@@ -38,7 +38,7 @@
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0004e0 20 20 20 20 20 20 20 20 00 00 00 00 00 00 00 00
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0004f0 01 01 00 00 00 00 00 00 00 00 00 f0 3f 00 00 00
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000500 00 00 00 f0 3f 03 01 30 00 3c fb 73 00 00 00 00
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-000510 00 00 00 00 07 0a 8b 00 00 01 46 0d 17 00 00 00
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+000510 00 00 00 00 06 0a 8b 00 00 01 46 0d 17 00 00 00
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000520 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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000530 00 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
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000540 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 |
The difference is for a clustered index leaf page record that starts at 0x50c. The DB_TRX_ID=0x70a would be incorrectly recovered as 0x60a. This difference was caught thanks to MDEV-18976.
The columns of the index seem to be something like the following:
(id INT UNSIGNED NOT NULL, DB_TRX_ID, DB_ROLL_PTR, pad CHAR(60), c CHAR(120), k INT, geocol2 GEOMETRY, tcol CHAR(3)).
On recovery, the incorrect byte was recovered by the following:
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10.6 92032499874259bae7455130958ea7f38c4d53a3 |
(rr) frame 2
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#2 0x000055f5b96c8359 in page_apply_insert_dynamic (block=..., reuse=false,
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prev=0, shift=0, enc_hdr_l=23, hdr_c=0, data_c=9, data=0x4e0c52e6e807,
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data_len=212)
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at /data/Server/bb-10.6-MDEV-29374/storage/innobase/page/page0cur.cc:2838
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2838 memcpy(buf, prev_rec, data_c);
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The buf starts at 0x50c (the start of the first column), and the prev_rec at offset 0x63 contains the following:
(rr) p/x *prev_rec@data_c
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$12 = {0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x6}
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It is worth noting that right after the incorrect data had been copied, that prev_rec field would have been adjusted to the correct value:
#0 mach_write_to_1 (b=0x4e0c5298806b "\a", n=7)
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at /data/Server/bb-10.6-MDEV-29374/storage/innobase/include/mach0data.inl:45
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#1 0x000055f5b96b4204 in rec_set_bit_field_1 (rec=0x4e0c52988070 "", val=7,
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offs=5, mask=15, shift=0)
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at /data/Server/bb-10.6-MDEV-29374/storage/innobase/include/rem0rec.inl:159
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#2 0x000055f5b96c83ab in page_apply_insert_dynamic (block=..., reuse=false,
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prev=0, shift=0, enc_hdr_l=23, hdr_c=0, data_c=9, data=0x4e0c52e6e807,
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data_len=212)
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at /data/Server/bb-10.6-MDEV-29374/storage/innobase/page/page0cur.cc:2842
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…
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(rr) frame 2
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#2 0x000055f5b96c83ab in page_apply_insert_dynamic (block=..., reuse=false,
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prev=0, shift=0, enc_hdr_l=23, hdr_c=0, data_c=9, data=0x4e0c52e6e807,
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data_len=212)
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at /data/Server/bb-10.6-MDEV-29374/storage/innobase/page/page0cur.cc:2842
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2842 rec_set_bit_field_1(owner_rec, n_owned + 1, REC_NEW_N_OWNED,
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Offset 0x63 is where the page infimum pseudo-record is stored. Because an instant ADD/DROP COLUMN has been executed on this table, the record will not contain the string infimum but something else (NUL bytes followed by the header of the supremum record).
I think that we must ‘pessimize’ the implementation of MDEV-21724 and never write log that would copy something from the infimum record to the first actual user record in the table.
Attachments
Issue Links
- causes
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- Closed
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- is caused by
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- Closed
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- relates to
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MDEV-15562 Instant DROP COLUMN or changing the order of columns
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- Closed
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- Closed
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- Closed
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- Closed
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