* Add the change log for 7.7
Add the change log for 7.7
* Update rel. notes to latest state (BC5)
Update the release notes to current state (i.e. BC5).
* Update docs/reference/release-notes/7.7.asciidoc
Co-Authored-By: James Rodewig <james.rodewig@elastic.co>
We found some problems during the test.
Data: 200Million docs, 1 shard, 0 replica
hits | avg | sum | value_count |
----------- | ------- | ------- | ----------- |
20,000 | .038s | .033s | .063s |
200,000 | .127s | .125s | .334s |
2,000,000 | .789s | .729s | 3.176s |
20,000,000 | 4.200s | 3.239s | 22.787s |
200,000,000 | 21.000s | 22.000s | 154.917s |
The performance of `avg`, `sum` and other is very close when performing
statistics, but the performance of `value_count` has always been poor,
even not on an order of magnitude. Based on some common-sense knowledge,
we think that `value_count` and sum are similar operations, and the time
consumed should be the same. Therefore, we have discussed the agg
of `value_count`.
The principle of counting in es is to traverse the field of each
document. If the field is an ordinary value, the count value is
increased by 1. If it is an array type, the count value is increased
by n. However, the problem lies in traversing each document and taking
out the field, which changes from disk to an object in the Java
language. We summarize its current problems with Elasticsearch as:
- Number cast to string overhead, and GC problems caused by a large
number of strings
- After the number type is converted to string, sorting and other
unnecessary operations are performed
Here is the proof of type conversion overhead.
```
// Java long to string source code, getChars is very time-consuming.
public static String toString(long i) {
int size = stringSize(i);
if (COMPACT_STRINGS) {
byte[] buf = new byte[size];
getChars(i, size, buf);
return new String(buf, LATIN1);
} else {
byte[] buf = new byte[size * 2];
StringUTF16.getChars(i, size, buf);
return new String(buf, UTF16);
}
}
```
test type | average | min | max | sum
------------ | ------- | ---- | ----------- | -------
double->long | 32.2ns | 28ns | 0.024ms | 3.22s
long->double | 31.9ns | 28ns | 0.036ms | 3.19s
long->String | 163.8ns | 93ns | 1921 ms | 16.3s
particularly serious.
Our optimization code is actually very simple. It is to manage different
types separately, instead of uniformly converting to string unified
processing. We added type identification in ValueCountAggregator, and
made special treatment for number and geopoint types to cancel their
type conversion. Because the string type is reduced and the string
constant is reduced, the improvement effect is very obvious.
hits | avg | sum | value_count | value_count | value_count | value_count | value_count | value_count |
| | | double | double | keyword | keyword | geo_point | geo_point |
| | | before | after | before | after | before | after |
----------- | ------- | ------- | ----------- | ----------- | ----------- | ----------- | ----------- | ----------- |
20,000 | 38s | .033s | .063s | .026s | .030s | .030s | .038s | .015s |
200,000 | 127s | .125s | .334s | .078s | .116s | .099s | .278s | .031s |
2,000,000 | 789s | .729s | 3.176s | .439s | .348s | .386s | 3.365s | .178s |
20,000,000 | 4.200s | 3.239s | 22.787s | 2.700s | 2.500s | 2.600s | 25.192s | 1.278s |
200,000,000 | 21.000s | 22.000s | 154.917s | 18.990s | 19.000s | 20.000s | 168.971s | 9.093s |
- The results are more in line with common sense. `value_count` is about
the same as `avg`, `sum`, etc., or even lower than these. Previously,
`value_count` was much larger than avg and sum, and it was not even an
order of magnitude when the amount of data was large.
- When calculating numeric types such as `double` and `long`, the
performance is improved by about 8 to 9 times; when calculating the
`geo_point` type, the performance is improved by 18 to 20 times.
This is a simple naming change PR, to fix the fact that "metadata" is a
single English word, and for too long we have not followed general
naming conventions for it. We are also not consistent about it, for
example, METADATA instead of META_DATA if we were trying to be
consistent with MetaData (although METADATA is correct when considered
in the context of "metadata"). This was a simple find and replace across
the code base, only taking a few minutes to fix this naming issue
forever.
The joda to java.time migration requires users to upgrade their mappings. We allow them to still use 6.x created indices with joda patterns in 7 but ask them to upgrade their patterns in 7.x.
This migration guide is to help them understand how they could be affected and what needs to be changed in their mappings.
closes#51614closes#51236
7.5 and 7.6 had a regression that allowed for
script_score queries to have negative scores.
We have corrected this regression in #52478.
This is an addition to #52478 that adds
a test and release notes.
Backport of #51233 to the seven dot x branch.
Tries to load a `Mapper` instance for the mapping snippet of a dynamic template.
This should catch things like using an analyzer that is undefined or mapping attributes that are unused.
This is best effort:
* If `{{name}}` placeholder is used in the mapping snippet then validation is skipped.
* If `match_mapping_type` is not specified then validation is performed for all mapping types.
If parsing succeeds with a single mapping type then this the dynamic mapping is considered valid.
If is detected that a dynamic template mapping snippet is invalid at mapping update time then the mapping update is failed for indices created on 8.0.0-alpha1 and later. For indices created on prior version a deprecation warning is omitted instead. In 7.x clusters the mapping update will never fail in case of an invalid dynamic template mapping snippet and a deprecation warning will always be omitted.
Closes#17411Closes#24419
Co-authored-by: Adrien Grand <jpountz@gmail.com>
István Zoltán Szabó
Paul Sanwald
Adrien Grand
Lisa Cawley
Bogdan Pintea
Nik Everett
qiye
Jason Tedor
James Rodewig
Jim Ferenczi
Przemyslaw Gomulka
Mayya Sharipova
Yannick Welsch
Martijn van Groningen
Zachary Tong
Zachary Tong
Colin Goodheart-Smithe
Hendrik Muhs
Deb Adair
Tom Callahan
Ioannis Kakavas