The document summarizes a presentation given by Marco Tusa and Aleksandr Kuzminsky on using the Percona Data Recovery Tool for InnoDB to recover data from corrupted or missing InnoDB files. It introduces the speakers and outlines how the tool can be used to extract data from ibdata files, attach .ibd files after corruption, recover deleted records, recover dropped tables, and recover from wrong updates by parsing binary logs. Examples are provided of running the tool's page_parser, constraints_parser and sys_parser components to extract schema and data.

1. Percona Live Santa Clara 2014
Be the hero of the day with Data
recovery for InnoDB
Marco Tusa – Aleksandr Kuzminsky
April 2014

2. Who
• Marco “The Grinch”
• Manager Rapid Response
• Former Pythian MySQL cluster
technical leader
• Former MySQL AB PS (EMEA)
• Love programming
• History of religions
• Ski; Snowboard; scuba diving;
Mountain trekking
2

3. What we will cover
• Recovery toolkit introduction
• Show how to extract data from IBD data file
• Attach ibd files after IBDATA corruption
• Recover deleted records
• Recover drop table
• Bad update
3

4. What is Percona Data recovery Tool for InnoDB
• Set of open source tools
• Work directly on the data files
• Recover lost data (no backup available)
• Wrappers (you can help)
4
A

5. What files?
• Server wide files
– <Table>.frm
• InnoDB files
– ibdata1
• InnoDB dictionary
• UNDO segment
• All tables if innodb_file_per_table=OFF
– <Table>.ibd
– Reads raw partition
5
A

6. InnoDB file format
• Antelope
– REDUNDANT (versions 4.x)
– COMPACT (5.X)
• Barracuda
– REDUNDANT, COMPACT
– New time formats in BARRACUDA
– COMPRESSED
6
A

7. What is a InnoDB Table space?
Tablespace consists of pages
• InnoDB page
– 16k by default
– page_id is file offset in 16k chunks
– Records never fragmented
– Types:
• FIL_PAGE_INDEX
• FIL_PAGE_TYPE_BLOB
• FIL_PAGE_UNDO_LOG
7
A

8. InnoDB index (B+ Tree) 8
A

9. Requirements and minimal skill to use the tool
• You need to know how to compile (make)
• MySQL you know what it is right?
• How to import data from a tab separated file
9
M

10. Show the tool in action - Process
Process:
10
data extraction
Extract data
From ibdataX
Read SYS_X
Tables
Generate Table
filters files
Extract data from
ibd Tbspaces
Validate Data
Import data back
Final clean up
Production
ready

11. Show the tool in action - page_parser
• Extract pages from InnoDB files
– (In case of innodb_file_per_table =0 it also extract real data)
– page_parser -f ibdata1 (or table space like employees.ibd)
11
Extract data from idbata

12. Show the tool in action – contraints_parser
• Extract data from InnoDB pages
• IE SYS_TABLE/INDEX/COLUMN
– bin/constraints_parser.SYS_TABLES -4Uf
FIL_PAGE_INDEX/0-1
– bin/constraints_parser.SYS_INDEXES -4Uf
FIL_PAGE_INDEX/0-3
12
Extract data from idbata

13. Show the tool in action - contraints_parser
Output
SYS_TABLES "employees/salaries" 811 
…
SYS_INDEXES 811 1889 "PRIMARY“ 
SYS_INDEXES 811 1890 "emp_no"
Table ID Index Id
13
Read SYS_Tables/Indexes

14. Show the tool in action - sys_parser
Why:
Lost FRM file
Two possible ways:
• Easy: copy it from slave/backup
• Less easy:
– Run sys_parser on a new create instance (info not accessible – require
dictionary table load)
14
Lost FRM and IBD (1)

15. Show the tool in action - sys_parser
Output:
./sys_parser -h192.168.0.35 -u stress -p tool –d <database>
employees/salaries
CREATE TABLE `salariesR`(
`emp_no` INT NOT NULL,
`salary` INT NOT NULL,
`from_date` DATE NOT NULL,
`to_date` DATE NOT NULL,
PRIMARY KEY (`emp_no`, `from_date`)) ENGINE=InnoDB;
15
Lost FRM and IBD (2)

16. Show the tool in action - ibdconnect
• Accidental removal of the IBDATA file
• IBDATA table space corruption
• Only file per table available (IE employees.ibd)
16
Attach Table from another source (1)

17. Show the tool in action - ibdconnect
What to do?
1. Start a new clean MySQL
2. Create empty structure
(same tables definition)
3. Copy over the table spaces
4. Run ibdconnect
5. Run
innochecksum_changer
17
Attach Table from another source (2)
./ibdconnect -o ibdata1 -f salaries.ibd -d
employees -t salaries
salaries.ibd belongs to space #15
Initializing table definitions...
Updating employees/salaries (table_id 797)
SYS_TABLES is updated successfully
Initializing table definitions...
Processing table: SYS_TABLES
…
Processing table: SYS_INDEXES
Setting SPACE=15 in SYS_INDEXES for TABLE_ID =
797

18. Show the tool in action – fix filters
Table filters use for:
• Identify the data inside the ibd
• Filter out the damage records
• Bound to table definition
• Must recompile for each table definition
• Generated with the tool create_def.pl
18
Generate Table filters (1)

19. Show the tool in action - page_parser filters
• Generated with the tool create_def.pl
create_defs.pl --db=$schema --table=$table >
$myPath/include/table_defs.${schema}.$table.defreco
very
• Create symbolic link to include/table_defs.h
• Compile again
19
Generate Table filters (1)

20. Show the tool in action - constraints_parser
The data is extracted by the tool specifying the table
space an possible BLOB directory.
/constraints_parser -5Uf FIL_PAGE_INDEX/0-${INDEXID} –b FIL_PAGE_TYPE_BLOB/ >
$DESTDIR/${SCHEMA}_${TABLE}.csv“
FIL_PAGE_INDEX/0-${INDEXID} is the ID of the PK
FIL_PAGE_TYPE_BLOB is the directory containing the BLOB
21
Extract data from Table space (1)

21. Show the tool in action - constraints_parser
Example of the data:
-- Page id: 4, Format: COMPACT, Records list: Valid, Expected records: (164 164)
00000000150B 88000002260084 employees 10001 "1953-09-02“ "G" "eorgiF" "(null)" "12722-11-12"
00000000150B 88000002260091 employees 10002 "1964-06-02" "B" "ezalelS“ "(null)" "14006-11-05"
00000000150B 8800000226009E employees 10003 "1959-12-03" "P" "artoB" "(null)" "14003-03-15"
00000000150B 880000022600AB employees 10004 "1954-05-01" "C" "hirstianK""(null)“ "12598-03-09"
00000000150B 880000022600B8 employees 10005 "1955-01-21" "K" "yoichiM" "(null)" "13876-11-14"
<snip>
00000000150B 880000022608EE employees 10164 "1956-01-19" "J" "agodaB" "(null)" "12474-11-14"
-- Page id: 4, Found records: 164, Lost records: NO, Leaf page: YES
22
Validate data

22. Show the tool in action - LOAD DATA INFILE
How to import the data back?
Easy as:
LOAD DATA INFILE ‘PLMC_employees/employees' REPLACE INTO
TABLE `employees` FIELDS TERMINATED BY 't' OPTIONALLY
ENCLOSED BY '"' LINES STARTING BY 'employeest' (`emp_no`,
`birth_date`, `first_name`, `last_name`, `gender`,
`hire_date`);
Done
23
Import data back

23. How recover deleted record -
Identify the records just for this exercise:
select count(emp_no) from employeesR where hire_date > '1999-08-24';
+---------------+
| count(emp_no) |
+---------------+
| 279 |
+---------------+
1 row in set (0.23 sec)
And bravely delete them:
delete from employeesR where hire_date > '1999-08-24';
Query OK, 279 rows affected (0.55 sec)
24
Delete records

24. How recover deleted record -
To recover deleted record we must use the –D flag:
constraints_parser -5Df /FIL_PAGE_INDEX/0-1975 -b
/FIL_PAGE_TYPE_BLOB/ > employees_employeesDeleted.csv
cat employees_employeesDeleted.csv |grep -i -v -e "-- Page id"|wc -l
55680  Too many because I take unfiltered records
25
Recover delete records

25. How recover deleted record -
name: "employeesR",
{
{ /* int(11) */
name: "emp_no",
type: FT_INT,
fixed_length: 4,
has_limits: TRUE,
limits: {
can_be_null: FALSE,
int_min_val: 10001,
int_max_val: 499999
},
26
Use filters to clean up results
name: "first_name",
type: FT_CHAR,
min_length: 0,
max_length: 42,
has_limits: TRUE,
limits: {
can_be_null: FALSE,
char_min_len: 3,
char_max_len: 42,
char_ascii_only: TRUE
},
can_be_null: FALSE
},
name: "last_name",
type: FT_CHAR,
min_length: 0,
max_length: 48,
has_limits: TRUE,
limits: {
can_be_null: FALSE,
char_min_len: 3,
char_max_len: 48,
char_ascii_only: TRUE
},

26. How recover deleted record -
Now let us recompile and run the extraction again:
cat employees_employeesDeleted.csv |grep -i -v -e "-- Page
id"|wc -l
279 <------ Bingo!
27
Check if it fits and reload

27. How recover Drop tables -
• Different methods if using innodb_file_per_table=[0|1].
– Must act fast because files can be overwritten quickly
• In the first case pages are mark free for reuse
• In the second the file is removed and we need to scan
the device
28

28. How recover Drop tables -
What we need then ?
• The table definition
• The PK index
– Parse the dictionary with the “D” flag
• constraints_parser.SYS_TABLES -4D
• Extract the InnoDB pages
29

29. How recover Drop tables -
Not using innodb_file_per_table method:
1. Extract the ibdataX as usual
2. Run contraints_parser
constraints_parser -5Uf ./FIL_PAGE_INDEX/0-1975 -b
./FIL_PAGE_TYPE_BLOB/ > employees_employeesDroped.csv
cat employees_employeesDroped.csv |grep -i -v -e "-- Page id"|wc -l
300024 <---- done
30
Not using file per table

30. How recover Drop tables -
Innodb_file_per_table=1 method:
What we need more?
• To know what device is containing the dropped
table
31
using file per table

31. How recover Drop tables -
Identify the PK id from dictionary:
cat SYS_TABLE.csv|grep employeesR
SYS_TABLES "employees/employeesR" 855
cat SYS_INDEX.csv|grep 855
SYS_INDEXES 855 1979 "PRIMARY”
32
using file per table

32. How recover Drop tables -
This time we must run the page_parser against the device
not the file using the T option.
-T -- retrieves only pages with index id = NM (N - high
word, M - low word of id)
page_parser -t 100G -T 0:1979 -f /dev/mapper/EXT_VG-extlv
Parse in this case take longer.
33
Run the page extraction

33. How recover wrong updates -
Doing with the tool is possible when new data is larger
then the original, and will not fit in the original page,
otherwise the old one will be replaced, as such the only
way is to parse the undo segment.
Tools: s_indexes, s_tables recover the dictionary from the
undo.
34

34. How recover wrong updates -
Other method:
Possible to use the binary log for that
When in ROW format .
35

35. How recover wrong updates -
You can use binary log to recover your data if:
• Binlog format = ROW
• binlog_row_image = FULL (from 5.6 you can change it)
36
Prerequisite

36. How recover wrong updates -
Assume a table like :
+--------+------------+------------+-----------+--------+------------+
| emp_no | birth_date | first_name | last_name | gender | hire_date |
+--------+------------+------------+-----------+--------+------------+
| 10001 | 1953-09-02 | Georgi | Facello | M | 1986-06-26 |
| 10002 | 1964-06-02 | Bezalel | Simmel | F | 1985-11-21 |
| 10003 | 1959-12-03 | Parto | Bamford | M | 1986-08-28 |
+--------+------------+------------+-----------+--------+------------+
An action like :
update employeesR set last_name="WRONG-NAME" where emp_no <
10010;
37
Scenario (1)

37. How recover wrong updates -
You will have to recover something like:
+--------+------------+------------+------------+--------+------------+
| emp_no | birth_date | first_name | last_name | gender | hire_date |
+--------+------------+------------+------------+--------+------------+
| 10001 | 1953-09-02 | Georgi | WRONG-NAME | M | 1986-06-26 |
| 10002 | 1964-06-02 | Bezalel | WRONG-NAME | F | 1985-11-21 |
| 10003 | 1959-12-03 | Parto | WRONG-NAME | M | 1986-08-28 |
…
38
Scenario (2)

38. How recover wrong updates -
with a simple command like :
mysqlbinlog -vvv logs/binlog.000034 --start-datetime="2014-03-19
11:00:07"|grep -e "@1" -e "@4"|awk -F '/*' '{print $1}'|awk '{print
$2}'
@1=10001
@4='Facello'
@1=10001
@4='WRONG-NAME'
@1=10002
@4='Simmel'
@1=10002
@4='WRONG-NAME'..
39
Recover from binary log (2)

39. Reference and repositories
Main Percona branch:
bzr branch lp:percona-data-recovery-tool-for-innodb
Marco branch:
https://github.com/Tusamarco/drtools
40
Recover from binary log (2)

40. Q&A 41

41. Contacts 42
To contact Marco
marco.tusa@percona.com
marcotusa@tusacentral.net
To follow me
http://www.tusacentral.net/
https://www.facebook.com/marco.tusa.94
@marcotusa
http://it.linkedin.com/in/marcotusa/
To contact Aleksander
aleksandr.kuzminsky@percona.com
To follow me
http://www.mysqlperformanceblog.com/author/akuzminsk
y/
https://www.linkedin.com/in/akuzminsky