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Add COALESCE and NULLIF to the logical plan #1404

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merged 3 commits into from
Mar 29, 2024
Merged

Add COALESCE and NULLIF to the logical plan #1404

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808bbf7
Add NULLIF and COALESCE to the logical plan
alancai98 Mar 28, 2024
b30605d
Merge branch 'main' into add-coalesce-nullif-to-plan
alancai98 Mar 29, 2024
0ce27b7
Align plan modeling of NULLIF to ast; fix expansion of Any in dynamic…
alancai98 Mar 29, 2024
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3 changes: 2 additions & 1 deletion CHANGELOG.md
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Expand Up @@ -32,6 +32,7 @@ Thank you to all who have contributed!

### Changed
- Change `StaticType.AnyOfType`'s `.toString` to not perform `.flatten()`
- Change modeling of `COALESCE` and `NULLIF` to dedicated nodes in logical plan

### Deprecated

Expand All @@ -43,7 +44,7 @@ Thank you to all who have contributed!

### Contributors
Thank you to all who have contributed!
- @<your-username>
- @alancai98

## [0.14.4]

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9 changes: 9 additions & 0 deletions partiql-plan/src/main/resources/partiql_plan.ion
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Expand Up @@ -135,6 +135,15 @@ rex::{
],
},

nullif::{
v1: rex,
v2: rex
},

coalesce::{
args: list::[rex]
},

collection::{
values: list::[rex],
},
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45 changes: 45 additions & 0 deletions partiql-planner/src/main/kotlin/org/partiql/planner/internal/ir/Nodes.kt
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Expand Up @@ -51,10 +51,12 @@ import org.partiql.planner.internal.ir.builder.RexOpCallDynamicCandidateBuilder
import org.partiql.planner.internal.ir.builder.RexOpCallStaticBuilder
import org.partiql.planner.internal.ir.builder.RexOpCaseBranchBuilder
import org.partiql.planner.internal.ir.builder.RexOpCaseBuilder
import org.partiql.planner.internal.ir.builder.RexOpCoalesceBuilder
import org.partiql.planner.internal.ir.builder.RexOpCollectionBuilder
import org.partiql.planner.internal.ir.builder.RexOpErrBuilder
import org.partiql.planner.internal.ir.builder.RexOpGlobalBuilder
import org.partiql.planner.internal.ir.builder.RexOpLitBuilder
import org.partiql.planner.internal.ir.builder.RexOpNullifBuilder
import org.partiql.planner.internal.ir.builder.RexOpPathIndexBuilder
import org.partiql.planner.internal.ir.builder.RexOpPathKeyBuilder
import org.partiql.planner.internal.ir.builder.RexOpPathSymbolBuilder
Expand Down Expand Up @@ -312,6 +314,8 @@ internal data class Rex(
is Path -> visitor.visitRexOpPath(this, ctx)
is Call -> visitor.visitRexOpCall(this, ctx)
is Case -> visitor.visitRexOpCase(this, ctx)
is Nullif -> visitor.visitRexOpNullif(this, ctx)
is Coalesce -> visitor.visitRexOpCoalesce(this, ctx)
is Collection -> visitor.visitRexOpCollection(this, ctx)
is Struct -> visitor.visitRexOpStruct(this, ctx)
is Pivot -> visitor.visitRexOpPivot(this, ctx)
Expand Down Expand Up @@ -567,6 +571,47 @@ internal data class Rex(
}
}

internal data class Nullif(
@JvmField
internal val v1: Rex,
@JvmField
internal val v2: Rex,
) : Op() {
internal override val children: List<PlanNode> by lazy {
val kids = mutableListOf<PlanNode?>()
kids.add(v1)
kids.add(v2)
kids.filterNotNull()
}

internal override fun <R, C> accept(visitor: PlanVisitor<R, C>, ctx: C): R =
visitor.visitRexOpNullif(this, ctx)

internal companion object {
@JvmStatic
internal fun builder(): RexOpNullifBuilder = RexOpNullifBuilder()
}
}

internal data class Coalesce(
@JvmField
internal val args: List<Rex>,
) : Op() {
override val children: List<PlanNode> by lazy {
val kids = mutableListOf<PlanNode?>()
kids.addAll(args)
kids.filterNotNull()
}

override fun <R, C> accept(visitor: PlanVisitor<R, C>, ctx: C): R =
visitor.visitRexOpCoalesce(this, ctx)

internal companion object {
@JvmStatic
internal fun builder(): RexOpCoalesceBuilder = RexOpCoalesceBuilder()
}
}

internal data class Collection(
@JvmField internal val values: List<Rex>,
) : Op() {
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11 changes: 11 additions & 0 deletions partiql-planner/src/main/kotlin/org/partiql/planner/internal/transforms/PlanTransform.kt
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Expand Up @@ -180,6 +180,17 @@ internal object PlanTransform : PlanBaseVisitor<PlanNode, ProblemCallback>() {
branches = node.branches.map { visitRexOpCaseBranch(it, ctx) }, default = visitRex(node.default, ctx)
)

override fun visitRexOpNullif(node: Rex.Op.Nullif, ctx: ProblemCallback) =
org.partiql.plan.Rex.Op.Nullif(
v1 = visitRex(node.v1, ctx),
v2 = visitRex(node.v2, ctx),
)

override fun visitRexOpCoalesce(node: Rex.Op.Coalesce, ctx: ProblemCallback) =
org.partiql.plan.Rex.Op.Coalesce(
args = node.args.map { visitRex(it, ctx) }
)

override fun visitRexOpCaseBranch(node: Rex.Op.Case.Branch, ctx: ProblemCallback) =
org.partiql.plan.Rex.Op.Case.Branch(
condition = visitRex(node.condition, ctx), rex = visitRex(node.rex, ctx)
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47 changes: 13 additions & 34 deletions partiql-planner/src/main/kotlin/org/partiql/planner/internal/transforms/RexConverter.kt
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Expand Up @@ -30,8 +30,10 @@ import org.partiql.planner.internal.ir.identifierQualified
import org.partiql.planner.internal.ir.identifierSymbol
import org.partiql.planner.internal.ir.rex
import org.partiql.planner.internal.ir.rexOpCallStatic
import org.partiql.planner.internal.ir.rexOpCoalesce
import org.partiql.planner.internal.ir.rexOpCollection
import org.partiql.planner.internal.ir.rexOpLit
import org.partiql.planner.internal.ir.rexOpNullif
import org.partiql.planner.internal.ir.rexOpPathIndex
import org.partiql.planner.internal.ir.rexOpPathKey
import org.partiql.planner.internal.ir.rexOpPathSymbol
Expand Down Expand Up @@ -107,7 +109,7 @@ internal object RexConverter {
private fun visitExprCoerce(node: Expr, ctx: Env, coercion: Rex.Op.Subquery.Coercion = Rex.Op.Subquery.Coercion.SCALAR): Rex {
val rex = super.visitExpr(node, ctx)
return when (rex.op is Rex.Op.Select) {
true -> rex(StaticType.ANY, rexOpSubquery(rex.op as Rex.Op.Select, coercion))
true -> rex(StaticType.ANY, rexOpSubquery(rex.op, coercion))
else -> rex
}
}
Expand Down Expand Up @@ -439,44 +441,21 @@ internal object RexConverter {
return rex(type, call)
}

// coalesce(expr1, expr2, ... exprN) ->
// CASE
// WHEN expr1 IS NOT NULL THEN EXPR1
// ...
// WHEN exprn is NOT NULL THEN exprn
// ELSE NULL END
override fun visitExprCoalesce(node: Expr.Coalesce, ctx: Env): Rex = plan {
override fun visitExprCoalesce(node: Expr.Coalesce, ctx: Env): Rex {
val type = StaticType.ANY
val createBranch: (Rex) -> Rex.Op.Case.Branch = { expr: Rex ->
val updatedCondition = rex(type, negate(call("is_null", expr)))
rexOpCaseBranch(updatedCondition, expr)
val args = node.args.map { arg ->
visitExprCoerce(arg, ctx)
}

val branches = node.args.map {
createBranch(visitExpr(it, ctx))
}.toMutableList()

val defaultRex = rex(type = StaticType.NULL, op = rexOpLit(value = nullValue()))
val op = rexOpCase(branches, defaultRex)
rex(type, op)
val op = rexOpCoalesce(args)
return rex(type, op)
}

// nullIf(expr1, expr2) ->
// CASE
// WHEN expr1 = expr2 THEN NULL
// ELSE expr1 END
override fun visitExprNullIf(node: Expr.NullIf, ctx: Env): Rex = plan {
override fun visitExprNullIf(node: Expr.NullIf, ctx: Env): Rex {
val type = StaticType.ANY
val expr1 = visitExpr(node.value, ctx)
val expr2 = visitExpr(node.nullifier, ctx)
val id = identifierSymbol(Expr.Binary.Op.EQ.name.lowercase(), Identifier.CaseSensitivity.SENSITIVE)
val fn = fnUnresolved(id, true)
val call = rexOpCallStatic(fn, listOf(expr1, expr2))
val branches = listOf(
rexOpCaseBranch(rex(type, call), rex(type = StaticType.NULL, op = rexOpLit(value = nullValue()))),
)
val op = rexOpCase(branches.toMutableList(), expr1)
rex(type, op)
val expr1 = visitExprCoerce(node.value, ctx)
val expr2 = visitExprCoerce(node.nullifier, ctx)
val op = rexOpNullif(expr1, expr2)
return rex(type, op)
}

/**
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50 changes: 50 additions & 0 deletions partiql-planner/src/main/kotlin/org/partiql/planner/internal/typer/PlanTyper.kt
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Expand Up @@ -55,9 +55,11 @@ import org.partiql.planner.internal.ir.rexOpCallDynamic
import org.partiql.planner.internal.ir.rexOpCallDynamicCandidate
import org.partiql.planner.internal.ir.rexOpCallStatic
import org.partiql.planner.internal.ir.rexOpCaseBranch
import org.partiql.planner.internal.ir.rexOpCoalesce
import org.partiql.planner.internal.ir.rexOpCollection
import org.partiql.planner.internal.ir.rexOpErr
import org.partiql.planner.internal.ir.rexOpLit
import org.partiql.planner.internal.ir.rexOpNullif
import org.partiql.planner.internal.ir.rexOpPathIndex
import org.partiql.planner.internal.ir.rexOpPathKey
import org.partiql.planner.internal.ir.rexOpPathSymbol
Expand Down Expand Up @@ -760,6 +762,54 @@ internal class PlanTyper(
return rex(type, op)
}

// COALESCE(v1, v2,..., vN)
// ==
// CASE
// WHEN v1 IS NOT NULL THEN v1 -- WHEN branch always a boolean
// WHEN v2 IS NOT NULL THEN v2 -- WHEN branch always a boolean
// ... -- similarly for v3..vN-1
// ELSE vN
// END
// --> minimal common supertype of(<type v1>, <type v2>, ..., <type v3>)
override fun visitRexOpCoalesce(node: Rex.Op.Coalesce, ctx: StaticType?): Rex {
val args = node.args.map { visitRex(it, it.type) }.toMutableList()
val typer = DynamicTyper()
args.forEach { v ->
typer.accumulate(v.type)
}
val (type, mapping) = typer.mapping()
if (mapping != null) {
assert(mapping.size == args.size) { "Coercion mappings `len ${mapping.size}` did not match the number of COALESCE arguments `len ${args.size}`" }
for (i in args.indices) {
val (operand, target) = mapping[i]
if (operand == target) continue // skip; no coercion needed
val cast = env.fnResolver.cast(operand, target)
val rex = rex(type, rexOpCallStatic(fnResolved(cast), listOf(args[i])))
args[i] = rex
}
}
val op = rexOpCoalesce(args)
return rex(type, op)
}

// NULLIF(v1, v2)
// ==
// CASE
// WHEN v1 = v2 THEN NULL -- WHEN branch always a boolean
// ELSE v1
// END
// --> minimal common supertype of (NULL, <type v1>)
override fun visitRexOpNullif(node: Rex.Op.Nullif, ctx: StaticType?): Rex {
val v1 = visitRex(node.v1, node.v1.type)
val v2 = visitRex(node.v2, node.v2.type)
val typer = DynamicTyper()
typer.accumulate(NULL)
typer.accumulate(v1.type)
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Only add v1's type here. I found that posgresql actually does something different here. Per their docs:

The result has the same type as the first argument — but there is a subtlety. What is actually returned is the first argument of the implied = operator, and in some cases that will have been promoted to match the second argument's type. For example, NULLIF(1, 2.2) yields numeric, because there is no integer = numeric operator, only numeric = numeric.

Per my read of SQL-99, I can't find any mention of this promotion behavior, so leaving the result type as just the minimal common supertype of (<type v1>, null). Postgresql would do something like the minimal common supertype of (<type v1>, <type v2>, null).

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I believe we can skip the dynamic typer here. It's just type of union(v1, null).flatten() or something as simple as that

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Yeah I'll simplify it. I initially included the dynamic typer in case we wanted to follow what postgresql did, which is easy to do w/ the dynamic typer.

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Followup from offline discussion, will keep the dynamic typer here to ensure consistency with the typing of CASE WHEN and COALESCE.

val (type, _) = typer.mapping()
val op = rexOpNullif(v1, v2)
return rex(type, op)
}

/**
* In this context, Boolean means PartiQLValueType Bool, which can be nullable.
* Hence, we permit Static Type BOOL, Static Type NULL, Static Type Missing here.
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9 changes: 9 additions & 0 deletions partiql-planner/src/main/resources/partiql_plan_internal.ion
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Expand Up @@ -158,6 +158,15 @@ rex::{
],
},

nullif::{
v1: rex,
v2: rex
},

coalesce::{
args: list::[rex]
},

collection::{
values: list::[rex],
},
Expand Down
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