Add ValuesListBoundStatement for handling Values list statements

[tristanvuong2021]

The addBinding function ends up creating a separate query for every set of bindings. See pgjdbc/r2dbc-postgresql#527. When there are a lot of inserts or updates, this severely affects performance. This PR adds a class that has a similar function as addBinding, but instead uses a values list to create a single query for multiple inserts or updates.

[wfa-reviewable]

This change is 

[SanjayVas]

Reviewed 1 of 5 files at r1, all commit messages.
Reviewable status: 1 of 5 files reviewed, 2 unresolved discussions (waiting on @tristanvuong2021)

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src/main/kotlin/org/wfanet/measurement/common/db/r2dbc/StatementBuilder.kt line 23 at r2 (raw file):

/** An interface for creating a R2DBC [Statement]. */
interface StatementBuilder {

This shouldn't be called StatementBuilder, as the builder pattern involves a mutable object. What we want to pass to the transaction context is an immutable object that has already been "built".

Note that converting to a Statement is not "building".

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src/main/kotlin/org/wfanet/measurement/common/db/r2dbc/postgres/ValuesListBoundStatement.kt line 159 at r2 (raw file):

    /** Builds a [ValuesListBoundStatement] from this builder. */
    fun build(): ValuesListBoundStatement {

This should ultimately be building a BoundStatement. That is to say that we don't need a different BoundStatement type, but rather a separate DSL builder interface for building BoundStatements using value lists.

[tristanvuong2021]

Reviewable status: 0 of 5 files reviewed, 2 unresolved discussions (waiting on @SanjayVas)

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src/main/kotlin/org/wfanet/measurement/common/db/r2dbc/postgres/ValuesListBoundStatement.kt line 159 at r2 (raw file):

Previously, SanjayVas (Sanjay Vasandani) wrote…

This should ultimately be building a BoundStatement. That is to say that we don't need a different BoundStatement type, but rather a separate DSL builder interface for building BoundStatements using value lists.

Done.

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src/main/kotlin/org/wfanet/measurement/common/db/r2dbc/StatementBuilder.kt line 23 at r2 (raw file):

Previously, SanjayVas (Sanjay Vasandani) wrote…

This shouldn't be called StatementBuilder, as the builder pattern involves a mutable object. What we want to pass to the transaction context is an immutable object that has already been "built".

Note that converting to a Statement is not "building".

Done.

[SanjayVas]

Reviewed 1 of 4 files at r2, 4 of 4 files at r3, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @tristanvuong2021)

[stevenwarejones]

Reviewed 1 of 4 files at r2, 4 of 4 files at r3, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @tristanvuong2021)