feat: Support functional indexes

[chenzl25]

Is your feature request related to a problem? Please describe.

Functional indexes are useful when users want to create an index on a field of jsonb column.

Example:

create table t (j jsonb);
create index idx on t(j->'k');
create index idx2 on t(j->>'k');
select * from t where j->>'k' = 'abc';

• Support functional indexes creation. feat(frontend): support functional indexes creation #8976
• Support functional indexes selection. feat(optimizer): support functional index selection #9067
• Support indexes on expressions. feat(frontend): support indexes on pure expressions #9142
• Index distributed columns support functional columns. feat(frontend): support distributed by columns for functional indexes #9489

References:

• https://www.postgresql.org/docs/current/indexes-expressional.html
• https://dev.mysql.com/doc/refman/8.0/en/create-index.html#create-index-functional-key-parts

Describe the solution you'd like

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Describe alternatives you've considered

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Additional context

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[st1page]

should we need to support the expression in the INCLUDE clause? It might be useful if the json is big.

create table t (j jsonb);
create index idx on t(j->'k') include(j->'v1', j->'v2', (j->'abc')->'abcv1');

[chenzl25]

should we need to support the expression in the INCLUDE clause? It might be useful if the json is big.

create table t (j jsonb);
create index idx on t(j->'k') include(j->'v1', j->'v2', (j->'abc')->'abcv1');

PG doesn't support expressions in included columns, so I think we don't need to support it as well. BTW, you can always put these expressions at the end of the index columns to achieve the same goal.