This change fixes handling of these types of queries:
- Double quoted column names with special characters:
SELECT "column.name" FROM s3object
- Double quoted column names with reserved keywords:
SELECT "CAST" FROM s3object
- Table name as prefix for column names:
SELECT S3Object."CAST" FROM s3object
String x might contain trimming spaces. And it needs to be trimmed. For
example, in csv files, there might be trimming spaces in a field that
ought to meet a query condition that contains the value without
trimming spaces. This applies to both intCast and floatCast functions.
enable linter using golangci-lint across
codebase to run a bunch of linters together,
we shall enable new linters as we fix more
things the codebase.
This PR fixes the first stage of this
cleanup.
This commit modifies csv parser, a fork of golang csv
parser to support a custom quote escape character.
The quote escape character is used to escape the quote
character when a csv field contains a quote character
as part of data.
Force sum/average to be calculated as a float.
As noted in #8221
> run SELECT AVG(CAST (Score as int)) FROM S3Object on
```
Name,Score
alice,80
bob,81
```
> AWS S3 gives 80.5 and MinIO gives 80.
This also makes overflows much more unlikely.
Queue output items and reuse them.
Remove the unneeded type system in sql and just use the Go type system.
In best case this is more than an order of magnitude speedup:
```
BenchmarkSelectAll_1M-12 1 1841049400 ns/op 274299728 B/op 4198522 allocs/op
BenchmarkSelectAll_1M-12 14 84833400 ns/op 169228346 B/op 3146541 allocs/op
```
The SQL parser as it stands right now ignores alias for aggregate
result, e.g. `SELECT COUNT(*) AS thing FROM s3object` doesn't actually
return record like `{"thing": 42}`, it returns a record like `{"_1": 42}`.
Column alias for aggregate result is supported in AWS's S3 Select, so
this commit fixes that by respecting the `expr.As` in the expression.
Also improve test for S3 select
On top of testing a simple `SELECT` query, we want to test a few more
"advanced" queries (e.g. aggregation).
Convert existing tests into table driven tests[1], and add the new test
cases with "advanced" queries into them.
[1] - https://github.com/golang/go/wiki/TableDrivenTests
This change adds support for casting strings to Timestamp via CAST:
`CAST('2010T' AS TIMESTAMP)`
It also implements the following date-time functions:
- UTCNOW()
- DATE_ADD()
- DATE_DIFF()
- EXTRACT()
For values passed to these functions, date-types are automatically
inferred.
- New parser written from scratch, allows easier and complete parsing
of the full S3 Select SQL syntax. Parser definition is directly
provided by the AST defined for the SQL grammar.
- Bring support to parse and interpret SQL involving JSON path
expressions; evaluation of JSON path expressions will be
subsequently added.
- Bring automatic type inference and conversion for untyped
values (e.g. CSV data).
