- Support simple queries that do not select
data from tables. This is similar to `values ..`,
but allows to add aliases for expressions.
- Such selects can also be used in subqueries
- Examples:
```
select 1;
select (select count(*) from t);
select 2 as foo, 3 as bar;

select a from t
where b in (select 100)
```

- Support like operator with signature:

expr1 LIKE expr2 [ESCAPE expr3]

which returns TRUE only if expr1 matches the
string specified by expr2 (pattern). '_' in
pattern matches any single character, '%'
matches any character 0 or more times. All
other characters match itself according to
case.

- Optional escape clause specifies character
to use for escaping '_' and '%'

Arseniy Volynets authored 9 months ago and Arseniy Volynets committed 6 months ago

- For cacheable requests, we now send only cache required data needed to
execute the query if it is in the storage cache. If query is not in the
storage cache, storage returns empty result with flag indicating there
was a cache miss. Then coordinator sends the second round of requests to
replicasets where cache miss happened. It sends the full message there.
- Parameters for required message are now computed without compilation
to SyntaxPlan - Fixed parameter order in SyntaxPlan

feat: support ALTER SYSTEM. It allows to change whitelisted properties from _pico_property table. Currently, changes affect all tiers. Specifying tier will result in an error.

Co-Authored-by: Dmitry Rodionov <d.rodionov@picodata.io>

Co-Authored-by: Emir Vildanov <e.vildanov@picodata.io>

Previous implementation treated TRIM as an SQL built-in function,
but in reality it is a special expression in SQL. The main difference
is that "TRIM" is not a name but a reserved keyword, so it can't
be wrapped into double quotes. Moreover, if we treat it as a function,
we need some special hacks to handle a complicated logic in its
arguments. Now TRIM is a separated expression with a custom parsing
logic.

Previously we had problems parsing arithmetic operations like `b*b`.
Because of incorrect handling of the forbidden symbols in the names
we recognized `b*b` as a column name rather then a multiplication.