Repository navigation
tp: INTERVAL INTERSECTION OF pipelines clash with columns named interval in subqueries #8171
Description
We want pipelines to work in more places than a top-level statement: as the source of another pipeline, and later as a WITH body:
FROM (FROM thread_state |> WHERE dur > 0) |> INTERVAL FLATTEN ...
WITH finished AS (FROM thread_state |> WHERE dur > 0)
FROM finished |> ...To support these, the parser accepts a pipeline anywhere it accepts a subquery. That breaks ordinary SQL using a column named interval, as the android_netperf metric does:
SELECT (interval / 1e9) FROM tAfter (, the parser has to decide on the spot whether interval is a column or the start of INTERVAL INTERSECTION OF. It picks the pipeline, then fails at /. Pipelines starting with FROM are fine, because FROM can never be a column.
The stopgap is to accept only FROM pipelines as subqueries, and INTERVAL INTERSECTION OF pipelines only as a whole statement, a CREATE PERFETTO TABLE body or a pipeline source. That is not acceptable as the final answer: an intersection is a pipeline like any other and has to work everywhere a pipeline does.
This must be settled before the pipe syntax is stabilized. The options:
- Make intersection a stage, so every pipeline starts with
FROM:The first operand becomes special, as withFROM a AS x |> INTERVAL INTERSECT (b AS y, c AS z) PER utid
|> JOINin GoogleSQL's pipe syntax, and existing pipelines need rewriting. - Keep the syntax and have the tokenizer treat
intervalas the keyword only when the next words areINTERSECTION OF. syntaqlite already does this forWINDOW,OVERandFILTER, but those are hard-coded in its runtime, so it needs a way for a dialect to declare its own. CheckingOFas well matters:SELECT interval intersection FROM tis valid SQL, the columnintervalaliased asintersection. Nothing changes for users. - Reserve
INTERVAL. Not viable: every column namedintervalwould break.
Pipelines are still behind PERFETTO PRAGMA pipelines, so changing the syntax (option 1) is cheapest now.
Activity
[-]tp: INTERVAL INTERSECTION OF keeps pipelines from parsing as a select[/-][+]tp: INTERVAL INTERSECTION OF pipelines clash with columns named interval in subqueries[/+]tp: parse a pipeline wherever SQLite parses a select
tp: parse a pipeline wherever SQLite parses a select
tp: parse a pipeline wherever SQLite parses a select (#8172)