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MDEV-26519: Improved histograms: Make JSON parser efficient

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Previous JSON parser was using an API which made the parsing
inefficient: the same JSON contents was parsed again and again.

Switch to using a lower-level parsing API which allows to do
parsing in an efficient way.
This commit is contained in:
Sergei Petrunia
2021-12-02 11:54:10 +03:00
parent be55ad0d34
commit 1d14176ec4
7 changed files with 358 additions and 188 deletions
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43
mysql-test/main/statistics_json.result
View File

@ -4263,54 +4263,79 @@ UPDATE mysql.column_stats
SET histogram='["not-what-you-expect"]' WHERE table_name='t1_json';
FLUSH TABLES;
explain select * from t1_json limit 1;
ERROR HY000: Failed to parse histogram: Root JSON element must be a JSON object at offset 0.
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1_json ALL NULL NULL NULL NULL 10
Warnings:
Warning 4186 Failed to parse histogram for table test.t1_json: Root JSON element must be a JSON object at offset 1.
UPDATE mysql.column_stats
SET histogram='{"histogram_hb_v2":"not-histogram"}' WHERE table_name='t1_json';
FLUSH TABLES;
explain select * from t1_json limit 1;
ERROR HY000: Failed to parse histogram: A JSON array expected at offset 0.
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1_json ALL NULL NULL NULL NULL 10
Warnings:
Warning 4186 Failed to parse histogram for table test.t1_json: histogram_hb_v2 must contain an array at offset 35.
UPDATE mysql.column_stats
SET histogram='{"histogram_hb_v2":["not-a-bucket"]}'
WHERE table_name='t1_json';
FLUSH TABLES;
explain select * from t1_json limit 1;
ERROR HY000: Failed to parse histogram: Object expected at offset 19.
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1_json ALL NULL NULL NULL NULL 10
Warnings:
Warning 4186 Failed to parse histogram for table test.t1_json: Expected an object in the buckets array at offset 35.
UPDATE mysql.column_stats
SET histogram='{"histogram_hb_v2":[{"no-expected-members":1}]}'
WHERE table_name='t1_json';
FLUSH TABLES;
explain select * from t1_json limit 1;
ERROR HY000: Failed to parse histogram: .start member must be present and be a scalar at offset 20.
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1_json ALL NULL NULL NULL NULL 10
Warnings:
Warning 4186 Failed to parse histogram for table test.t1_json: "start" element not present at offset 45.
UPDATE mysql.column_stats
SET histogram='{"histogram_hb_v2":[{"start":{}}]}'
WHERE table_name='t1_json';
FLUSH TABLES;
explain select * from t1_json limit 1;
ERROR HY000: Failed to parse histogram: .start member must be present and be a scalar at offset 20.
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1_json ALL NULL NULL NULL NULL 10
Warnings:
Warning 4186 Failed to parse histogram for table test.t1_json: "size" element not present at offset 31.
UPDATE mysql.column_stats
SET histogram='{"histogram_hb_v2":[{"start":"aaa", "size":"not-an-integer"}]}'
WHERE table_name='t1_json';
FLUSH TABLES;
explain select * from t1_json limit 1;
ERROR HY000: Failed to parse histogram: .size member must be present and be a scalar at offset 20.
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1_json ALL NULL NULL NULL NULL 10
Warnings:
Warning 4186 Failed to parse histogram for table test.t1_json: "ndv" element not present at offset 60.
UPDATE mysql.column_stats
SET histogram='{"histogram_hb_v2":[{"start":"aaa", "size":0.25}]}'
WHERE table_name='t1_json';
FLUSH TABLES;
explain select * from t1_json limit 1;
ERROR HY000: Failed to parse histogram: .ndv member must be present and be a scalar at offset 20.
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1_json ALL NULL NULL NULL NULL 10
Warnings:
Warning 4186 Failed to parse histogram for table test.t1_json: "ndv" element not present at offset 48.
UPDATE mysql.column_stats
SET histogram='{"histogram_hb_v2":[{"start":"aaa", "size":0.25, "ndv":1}]}'
WHERE table_name='t1_json';
FLUSH TABLES;
explain select * from t1_json limit 1;
ERROR HY000: Failed to parse histogram: .end must be present in the last bucket and only there at offset 0.
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1_json ALL NULL NULL NULL NULL 10
UPDATE mysql.column_stats
SET histogram='{"histogram_hb_v2":[]}'
WHERE table_name='t1_json';
FLUSH TABLES;
explain select * from t1_json limit 1;
ERROR HY000: Failed to parse histogram: .end must be present in the last bucket and only there at offset 0.
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1_json ALL NULL NULL NULL NULL 10
Warnings:
Warning 4186 Failed to parse histogram for table test.t1_json: Histogram must have at least one bucket at offset 21.
create table t2 (
city varchar(100)
);