We speak of the term vectors of a document, where each field has an associated
stored term vector. Since by default we are requesting all the term vectors of
a document, the HTTP request endpoint should rather be called `_termvectors`
instead of `_termvector`. The usage of `_termvector` is now deprecated, as
well as the transport client call to termVector and prepareTermVector.
Closes#8484
Previous to this change all features (_alias,_mapping,_settings,_warmer) are run regardless of which features are actually requested. This change fixes the request object to resolve this bug
We currently use the djb2 hash function in order to compute the shard a
document should go to. Unfortunately this hash function is not very
sophisticated and you can sometimes hit adversarial cases, such as numeric ids
on 33 shards.
Murmur3 generates hashes with a better distribution, which should avoid the
adversarial cases.
Here are some examples of how 100000 incremental ids are distributed to shards
using either djb2 or murmur3.
5 shards:
Murmur3: [19933, 19964, 19940, 20030, 20133]
DJB: [20000, 20000, 20000, 20000, 20000]
3 shards:
Murmur3: [33185, 33347, 33468]
DJB: [30100, 30000, 39900]
33 shards:
Murmur3: [2999, 3096, 2930, 2986, 3070, 3093, 3023, 3052, 3112, 2940, 3036, 2985, 3031, 3048, 3127, 2961, 2901, 3105, 3041, 3130, 3013, 3035, 3031, 3019, 3008, 3022, 3111, 3086, 3016, 2996, 3075, 2945, 2977]
DJB: [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 900, 900, 900, 900, 1000, 1000, 10000, 10000, 10000, 10000, 9100, 9100, 9100, 9100, 9000, 9000, 0, 0, 0, 0, 0, 0]
Even if djb2 looks ideal in some cases (5 shards), the fact that the
distribution of its hashes has some patterns can raise issues with some shard
counts (eg. 3, or even worse 33).
Some tests have been modified because they relied on implementation details of
the routing hash function.
Close#7954
The MLT field query is simply replaced by a MLT query set to specififc field.
To simplify code maintenance we should deprecate it in 1.4 and remove it in
2.0.
Closes#8238
Adrien Grand
Alex Ksikes
Simon Willnauer
Colin Goodheart-Smithe