workload/schemachange: add support for CREATE FUNCTION

[chrisseto]

6e1ea5d workload/schemachange: add support for CREATE FUNCTION

This commit adds support for the CREATE FUNCTION DDL to the RSW.

While the space for possible UDF incantations is quite large, this
commit focused on permutations that are of interest to schema changes.
That is to say, the body of the UDF does not have much, if any,
variation but will be comprised of references to tables and UDTs.

Unfortunately, the introduction of UDFs in the descriptor graph has
aggravated an issue within DROP SCHEMA CASCADE.

This commit contains attempts to correct said issues to no avail. It's
possible that either the DSC or LSC are missing some logic for handling
UDFs that contain references to UDTs. Prior to this commit, errors
preventing the schema from being dropped would be thrown. After it,
expected errors are not thrown appropriately despite the checks being
hand verified for correctness.

Epic: CRDB-19168
Informs: CRDB-3265
Release note: None

[cockroach-teamcity]

This change is 

[fqazi]

This is really nice and readable. Great work @chrisseto!

Reviewed 4 of 4 files at r4, all commit messages.
Reviewable status: complete! 0 of 0 LGTMs obtained (waiting on @chrisseto, @herkolategan, and @srosenberg)

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pkg/workload/schemachange/operation_generator.go line 3771 at r4 (raw file):

func (og *operationGenerator) createFunction(ctx context.Context, tx pgx.Tx) (*opStmt, error) {
	tables, err := Collect(ctx, og, tx, pgx.RowTo[string], `SELECT quote_ident(schema_name) || '.' || quote_ident(table_name) FROM [SHOW TABLES] WHERE type = 'table'`)

Do we need to limit it to only tables? You could select from views / sequences too.

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pkg/workload/schemachange/operation_generator.go line 3818 at r4 (raw file):

	}

	// TODO(chrisseto): There's no randomization across STRICT, VOLATILE,

Maybe as a TODO we could do sequence references too..like nextval(..)

[chrisseto]

TFTR!

Reviewable status: complete! 0 of 0 LGTMs obtained (waiting on @fqazi, @herkolategan, and @srosenberg)

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pkg/workload/schemachange/operation_generator.go line 3771 at r4 (raw file):

Previously, fqazi (Faizan Qazi) wrote…

Do we need to limit it to only tables? You could select from views / sequences too.

Didn't even think about that! I've updated it to include views. sequences have been todo'd because they break DROP SEQUENCE.

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pkg/workload/schemachange/operation_generator.go line 3818 at r4 (raw file):

Previously, fqazi (Faizan Qazi) wrote…

Maybe as a TODO we could do sequence references too..like nextval(..)

Done.

[chrisseto]

bors r=fqazi

[craig]

Build succeeded:

• Bazel Essential CI (Cockroach)