VReplication: Support binlog_row_value_options=PARTIAL_JSON

[mattlord]

Description

This PR adds support for --binlog-row-value-options=PARTIAL_JSON. You can read more about this here.

This can offer big wins in specific cases. For example...

1. Let's say that you have a table with 1 JSON column, and the JSON document is often large.
2. You update just a single row, to update $.price from 99.99 to 102.99 (inflation) and the original JSON document is 5MiB.
3. Without binlog_row_value_options=PARTIAL_JSON the binlog event will have the full 5MiB document in the BEFORE (original) and AFTER (updated) images. So 10MiB now.
4. With the option enabled, the BEFORE image still has the 5MiB document but the AFTER image only has a handful of bytes to represent the diff operation, JSON_REPLACE in this case, along with the path of $.price and the value of 102.99. So we've cut the bytes stored on disk, sent over the wire, and processed in memory by ~ 1/2.

Now if you imagine that instead of updating a single row, you updated 10,000 rows... let's say to remove the $.on_sale flag on the documents that had it set (Black Friday is over), you can see the big savings that comes with it.

Important

With this option enabled, JSON columns that are NOT updated when a row is modified are elided from the AFTER images (similar to the binlog_row_image=NOBLOB behavior with BLOB/TEXT columns). So this also offers a big potential savings as you may be updating 10,000 rows in a table that happens to have a JSON column, but you're only changing some other column value(s).

Manual test:

make build

cd examples/local

./101_initial_cluster.sh; mysql < ../common/insert_commerce_data.sql; ./201_customer_tablets.sh
  
alias vtctldclient='command vtctldclient --server=localhost:15999'
  
mysql commerce -e "alter table customer add jd json; update customer set jd = '{\"salary\":100}'; update customer set jd = '{\"salary\":99}' where customer_id in (2,3,4)"
  
for uid in $(vtctldclient GetTablets | awk '{print $1}' | cut -d- -f2 | bc); do
  command mysql -u root --socket "${VTDATAROOT}/vt_0000000${uid}/mysql.sock" -e "set @@global.binlog_row_value_options=PARTIAL_JSON; set @@global.general_log=ON"
done
  
./202_move_tables.sh
  
commerce_primary_uid=$(vtctldclient GetTablets --keyspace commerce --tablet-type primary --shard "0" | awk '{print $1}' | cut -d- -f2 | bc)
customer_primary_uid=$(vtctldclient GetTablets --keyspace customer --tablet-type primary --shard "0" | awk '{print $1}' | cut -d- -f2 | bc)
  
command mysql -u root --socket "${VTDATAROOT}/vt_0000000${commerce_primary_uid}/mysql.sock" vt_commerce -e "update customer set jd = JSON_SET(jd, '$.role', 'manager')"
command mysql -u root --socket "${VTDATAROOT}/vt_0000000${commerce_primary_uid}/mysql.sock" vt_commerce -e "update customer set jd = JSON_SET(jd, '$.color', 'red')"
command mysql -u root --socket "${VTDATAROOT}/vt_0000000${commerce_primary_uid}/mysql.sock" vt_commerce -e "update customer set email = concat('new', email)"
  
sleep 2
command mysql -u root --socket "${VTDATAROOT}/vt_0000000${customer_primary_uid}/mysql.sock" vt_customer -e "select * from customer"
  
command mysql -u root --socket "${VTDATAROOT}/vt_0000000${commerce_primary_uid}/mysql.sock" vt_commerce -e "update customer set jd = JSON_SET(jd, '$.day', 'wednesday')"
command mysql -u root --socket "${VTDATAROOT}/vt_0000000${commerce_primary_uid}/mysql.sock" vt_commerce -e "update customer set jd = JSON_INSERT(JSON_REPLACE(jd, '$.day', 'friday'), '$.favorite_color', 'black')"
command mysql -u root --socket "${VTDATAROOT}/vt_0000000${commerce_primary_uid}/mysql.sock" vt_commerce -e "update customer set jd = JSON_SET(JSON_REMOVE(JSON_REPLACE(jd, '$.day', 'monday'), '$.favorite_color'), '$.hobby', 'skiing') where customer_id = 3"
  
sleep 2
command mysql -u root --socket "${VTDATAROOT}/vt_0000000${customer_primary_uid}/mysql.sock" vt_customer -e "select * from customer"
  
command mysql -u root --socket "${VTDATAROOT}/vt_0000000${commerce_primary_uid}/mysql.sock" vt_commerce -e "update customer set jd = JSON_SET(JSON_REMOVE(JSON_REPLACE(jd, '$.day', 'tuesday'), '$.favorite_color'), '$.hobby', 'skiing') where customer_id = 4"
command mysql -u root --socket "${VTDATAROOT}/vt_0000000${commerce_primary_uid}/mysql.sock" vt_commerce -e "update customer set jd = JSON_SET(JSON_SET(jd, '$.salary', 110), '$.role', 'IC') where customer_id = 4"
command mysql -u root --socket "${VTDATAROOT}/vt_0000000${commerce_primary_uid}/mysql.sock" vt_commerce -e "update customer set jd = JSON_SET(jd, '$.misc', '{\"address\":\"1012 S Park\", \"town\":\"Hastings\", \"state\":\"MI\"}') where customer_id = 1"
command mysql -u root --socket "${VTDATAROOT}/vt_0000000${commerce_primary_uid}/mysql.sock" vt_commerce -e "insert into customer (customer_id, email) values (10, '[email protected]'), (11, '[email protected]')"
command mysql -u root --socket "${VTDATAROOT}/vt_0000000${commerce_primary_uid}/mysql.sock" vt_commerce -e "update customer set jd = '\"null\"' where customer_id = 10"
command mysql -u root --socket "${VTDATAROOT}/vt_0000000${commerce_primary_uid}/mysql.sock" vt_commerce -e "update customer set jd = 'null' where customer_id = 11"
  
sleep 2
command mysql -u root --socket "${VTDATAROOT}/vt_0000000${customer_primary_uid}/mysql.sock" vt_customer -e "select * from customer"
  
command mysql -u root --socket "${VTDATAROOT}/vt_0000000${commerce_primary_uid}/mysql.sock" vt_commerce -e "update customer set customer_id=customer_id+100, jd=JSON_SET(jd, '$.day', 'friday')"
  
sleep 2
command mysql -u root --socket "${VTDATAROOT}/vt_0000000${customer_primary_uid}/mysql.sock" vt_customer -e "select * from customer"

With the final result:

+-------------+------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| customer_id | email                  | jd                                                                                                                                                                               |
+-------------+------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
|         101 | [email protected]    | {"day": "friday", "misc": "{\"address\":\"1012 S Park\", \"town\":\"Hastings\", \"state\":\"MI\"}", "role": "manager", "color": "red", "salary": 100, "favorite_color": "black"} |
|         102 | [email protected]      | {"day": "friday", "role": "manager", "color": "red", "salary": 99, "favorite_color": "black"}                                                                                    |
|         103 | [email protected]  | {"day": "friday", "role": "manager", "color": "red", "hobby": "skiing", "salary": 99}                                                                                            |
|         104 | [email protected]      | {"day": "friday", "role": "IC", "color": "red", "hobby": "skiing", "salary": 110}                                                                                                |
|         105 | [email protected]      | {"day": "friday", "role": "manager", "color": "red", "salary": 100, "favorite_color": "black"}                                                                                   |
|         110 | [email protected]  | "null"                                                                                                                                                                           |
|         111 | [email protected] | null                                                                                                                                                                             |
+-------------+------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

Related Issue(s)

• Fixes: Feature Request: Support more efficient JSON replication #17232

Checklist

• "Backport to:" labels have been added if this change should be back-ported to release branches
• If this change is to be back-ported to previous releases, a justification is included in the PR description
• Tests were added or are not required
• Did the new or modified tests pass consistently locally and on CI?
• Documentation: Add some documentation for https://github.com/vitessio/vitess/pull/17345 website#1906

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[codecov]

Codecov Report

Attention: Patch coverage is 59.04762% with 129 lines in your changes missing coverage. Please review.

Project coverage is 67.61%. Comparing base (dd4ec2e) to head (27edece).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...blet/tabletmanager/vreplication/replicator_plan.go	26.21%	76 Missing ⚠️
go/test/utils/binlog.go	48.00%	13 Missing ⚠️
go/mysql/binlog/binlog_json.go	89.71%	11 Missing ⚠️
go/mysql/binlog/rbr.go	38.46%	8 Missing ⚠️
...t/tabletmanager/vreplication/table_plan_partial.go	0.00%	8 Missing ⚠️
go/vt/vttablet/tabletserver/vstreamer/vstreamer.go	65.21%	8 Missing ⚠️
go/mysql/binlog_event_rbr.go	90.00%	3 Missing ⚠️
go/mysql/binlog_event_filepos.go	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #17345      +/-   ##
==========================================
- Coverage   67.64%   67.61%   -0.04%     
==========================================
  Files        1582     1583       +1     
  Lines      254000   254321     +321     
==========================================
+ Hits       171826   171952     +126     
- Misses      82174    82369     +195     

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[mattlord]

This didn't help with the periodic failures, but good to upgrade anyway as the latest GA is 5.1.

[mattlord]

This fixes a bug we had with NOBLOB support. Without this, the blob/text field value would be silently lost (detected by vdiff). Since NOBLOB support is experimental (even in v22), I do not think we need to backport it.

[mattlord]

This was a bug exposed in the VPlayerBatching, which was enabled by default in v22. Prior to v22 it was experimental and thus I don't think we need to backport this fix.

[rohit-nayak-ps]

Nice work!

[shlomi-noach]

Looks good! Asked for some comment clarifications, see inline. Basically I need a braindump of your knowledge to get a better understanding of how this works (the code is mostly too complex to just figure this out from the code).

[shlomi-noach]

Can you generally clarify (by code comments) what's going on here? (And otherwise in the rest of the function). I feel like there's some intimate knowledge here that I'm missing. What exactly needs to be done? What are we solving?

[mattlord]

Added here: 5deec92

[shlomi-noach]

Please explain the purpose of this Pseudo() function? What are custom implementations of GTID? (Also, I'm not sure I follow the connection to partial JSON. Is this specific for testing?)

[mattlord]

I don't know the answer to these things either. 🙂 I only moved it to more logically group the IsBlank functions together. I did not add it here.

It looks like dead code as it's only ever set to false:

go/mysql/binlog_event.go:       // IsPseudo is for custom implementations of GTID.
go/mysql/binlog_event.go:       IsPseudo() bool
go/mysql/binlog_event_common.go:// IsPseudo is always false for a native binlogEvent.
go/mysql/binlog_event_common.go:func (ev binlogEvent) IsPseudo() bool {
go/mysql/binlog_event_filepos.go:func (ev filePosFakeEvent) IsPseudo() bool {
go/vt/binlog/binlog_streamer.go:                case ev.IsPseudo():

It was added 7 years ago in #3950

[GrahamCampbell]

I'd be curious how battle tested this actually is, and if there are any MySQL bugs that may cause drift.

[mattlord]

I'd be curious how battle tested this actually is, and if there are any MySQL bugs that may cause drift.

I have no idea how widely the option is used across the global set of MySQL installations. I don't see any known bugs:

• https://bugs.mysql.com/search.php?search_for=partial_json&status=Active&severity=&limit=100&order_by=&cmd=display&direction=ASC&os=0&phpver=&bug_age=0
• https://bugs.mysql.com/search.php?search_for=json&status%5B%5D=Active&severity=&limit=100&order_by=&cmd=display&phpver=&os=0&os_details=&bug_age=0&cpu_arch=0&cpu_arch_details=&last_updated=0&tags=&similar=

It's worth noting that this feature has existed in MySQL GA releases now for over 6 years.