pingcap
tidb-configuration-file: add more notes to txn-entry-size-limit
What is changed, added or deleted? (Required)
Growing the txn-entry-size-limit to the maximum size needs adjustments in other settings as well.
When txn-entry-size-limit is too small:
sql> INSERT INTO t1(t) VALUES(REPEAT('x',6*1024*1024));
ERROR: 8025 (HY000): entry too large, the max entry size is 6291456, the size of data is 6291489
When raft-entry-max-size is too small:
sql> INSERT INTO t1(t) VALUES(REPEAT('x',15*1024*1024));
ERROR: 1105 (HY000): message:"raft entry is too large, region 2, entry size 15728790" raft_entry_too_large:<region_id:2 entry_size:15728790 >
When max_allowed_packet is too small:
sql> INSERT INTO t1(t) VALUES(REPEAT('x',100*1024*1024));
ERROR: 1301 (HY000): Result of repeat() was larger than max_allowed_packet (67108864) - truncated
When txn-total-size-limit is too small:
sql> INSERT INTO t1(t) VALUES(REPEAT('x',100*1024*1024));
ERROR: 8004 (HY000): Transaction is too large, size: 104857633
Tested with:
tiup playground --tiflash 0 --without-monitor --db.config /tmp/tidb.toml --kv.config /tmp/tikv.toml v6.3.0
tikv.toml:
[raftstore]
raft-entry-max-size = "150MB"
tidb.toml:
[performance]
txn-entry-size-limit = 125829120
txn-total-size-limit = 1073741824
And SET GLOBAL max_allowed_packet=130*1024*1024 (and then reconnect)
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- TomShawn
- qiancai
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Note that the actual limit might be slightly less. Instead of 6MiB (default config) exactly it is 33 bytes less for the defaults. I don't think this is a problem.
sql> CREATE TABLE t1(id bigint primary key auto_random, t longtext);
Query OK, 0 rows affected, 1 warning (0.1575 sec)
Note (code 1105): Available implicit allocation times: 288230376151711743
sql> INSERT INTO t1(t) VALUES(REPEAT('x',5*1024*1024));
Query OK, 1 row affected (0.0811 sec)
sql> INSERT INTO t1(t) VALUES(REPEAT('x',6*1024*1024));
ERROR: 8025 (HY000): entry too large, the max entry size is 6291456, the size of data is 6291489
sql> SELECT 6291489-6291456;
+-----------------+
| 6291489-6291456 |
+-----------------+
| 33 |
+-----------------+
1 row in set (0.0003 sec)
sql> INSERT INTO t1(t) VALUES(REPEAT('x',(6*1024*1024)-33));
Query OK, 1 row affected (0.0803 sec)
sql> SELECT LENGTH(t), FORMAT_BYTES(LENGTH(t)) FROM t1;
+-----------+-------------------------+
| LENGTH(t) | FORMAT_BYTES(LENGTH(t)) |
+-----------+-------------------------+
| 6291423 | 6.00 MiB |
| 5242880 | 5.00 MiB |
+-----------+-------------------------+
2 rows in set (0.0921 sec)
The ci / tidb-check found this:
tidb-configuration-file.md
365:24-365:87 warning Dead anchor: /system-variables.md#max_allowed_packet pingcap-docs-anchors remark-lint
However the link seems fine to me.
The
ci / tidb-checkfound this:tidb-configuration-file.md 365:24-365:87 warning Dead anchor: /system-variables.md#max_allowed_packet pingcap-docs-anchors remark-lintHowever the link seems fine to me.
Anchor fixed. If @qiancai has no further comment, let's merge this PR.
This pull request has been accepted and is ready to merge.