Support querying a data stream

[ketanv3]

Description

Fixed index expression resolution to include backing indices of a data stream. This will make querying a data stream consistent with querying an index alias.

Issues Resolved

• Closes [Feature] Support querying a data stream #55

Check List

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Signed-off-by: Ketan Verma ketan9495@gmail.com

[dai-chen]

Thanks for contributing this PR! Could you fix the unit test error in Github action?
Btw, data stream seems a x-pack feature. Are you using x-pack with our SQL plugin together?

2021-05-14T15:44:56.3441278Z com.amazon.opendistroforelasticsearch.sql.legacy.esdomain.mapping.FieldMappingsTest > flatFieldMappingsShouldIncludeFieldsOnAllLevels FAILED
2021-05-14T15:44:56.3444598Z     java.lang.IllegalStateException: Failed to read mapping in cluster state for indices=[field_mappings], types=[]
2021-05-14T15:44:56.3448366Z         at com.amazon.opendistroforelasticsearch.sql.legacy.esdomain.LocalClusterState.getFieldMappings(LocalClusterState.java:218)
2021-05-14T15:44:56.3457993Z         at com.amazon.opendistroforelasticsearch.sql.legacy.esdomain.LocalClusterState.getFieldMappings(LocalClusterState.java:172)
2021-05-14T15:44:56.3465882Z         at com.amazon.opendistroforelasticsearch.sql.legacy.esdomain.mapping.FieldMappingsTest.flatFieldMappingsShouldIncludeFieldsOnAllLevels(FieldMappingsTest.java:68)
2021-05-14T15:44:56.3471283Z 
2021-05-14T15:44:56.3471639Z         Caused by:
2021-05-14T15:44:56.3472259Z         java.lang.NullPointerException
2021-05-14T15:44:56.3473122Z             at java.base/java.util.Arrays.sort(Arrays.java:1040)
2021-05-14T15:44:56.3475761Z             at com.amazon.opendistroforelasticsearch.sql.legacy.esdomain.LocalClusterState.sortToList(LocalClusterState.java:251)
2021-05-14T15:44:56.3481108Z             at com.amazon.opendistroforelasticsearch.sql.legacy.esdomain.LocalClusterState.findMappingsInCache(LocalClusterState.java:244)
2021-05-14T15:44:56.3486622Z             at com.amazon.opendistroforelasticsearch.sql.legacy.esdomain.LocalClusterState.getFieldMappings(LocalClusterState.java:206)
2021-05-14T15:44:56.3489248Z             ... 2 more

[ketanv3]

@dai-chen Fixed the broken unit-tests.

We are adding data streams' support in OpenSearch which is being tracked here: opensearch-project/OpenSearch#675
We are also making sure that existing plugins are compatible with data streams once it's released.

[dai-chen]

LGTM. Just wondering any chance to add IT for this new feature? Example: https://github.com/opensearch-project/sql/blob/develop/integ-test/src/test/java/com/amazon/opendistroforelasticsearch/sql/sql/IdentifierIT.java

[dai-chen]

Sorry I just realized that my PR renaming all packages to org.opensearch impacts yours. Could you please address the conflicts or rebase your changes?

[ketanv3]

@dai-chen No worries! I have rebased with the 'develop' branch.