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Bug fix: fix emit pushdown for merge join (#121)
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* Push down complex expressions to a projection from join condition

* Bug fix: fix emit pushdown for merge join
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Ulimo authored Nov 14, 2023
1 parent c5ea1be commit 6a3646c
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,7 @@

using FlowtideDotNet.Substrait.Relations;
using System.ComponentModel.DataAnnotations;
using static SqlParser.Ast.DataType;

namespace FlowtideDotNet.Core.Optimizer.EmitPushdown
{
Expand Down Expand Up @@ -498,9 +499,41 @@ public override Relation VisitMergeJoinRelation(MergeJoinRelation mergeJoinRelat
List<int> leftEmit = new List<int>();
List<int> rightEmit = new List<int>();

Dictionary<int, int> leftEmitToInternal = new Dictionary<int, int>();
if (mergeJoinRelation.Left.EmitSet)
{
for (int i = 0; i < mergeJoinRelation.Left.Emit.Count; i++)
{
leftEmitToInternal.Add(i, mergeJoinRelation.Left.Emit[i]);
}
}
else
{
for (int i = 0; i < mergeJoinRelation.Left.OutputLength; i++)
{
leftEmitToInternal.Add(i, i);
}
}

Dictionary<int, int> rightEmitToInternal = new Dictionary<int, int>();
if (mergeJoinRelation.Right.EmitSet)
{
for (int i = 0; i < mergeJoinRelation.Right.Emit.Count; i++)
{
rightEmitToInternal.Add(i, mergeJoinRelation.Right.Emit[i]);
}
}
else
{
for (int i = 0; i < mergeJoinRelation.Right.OutputLength; i++)
{
rightEmitToInternal.Add(i, i);
}
}

foreach (var field in leftUsage)
{
leftEmit.Add(field);
leftEmit.Add(leftEmitToInternal[field]);
oldToNew.Add(field, replacementCounter);
replacementCounter += 1;
}
Expand All @@ -509,7 +542,7 @@ public override Relation VisitMergeJoinRelation(MergeJoinRelation mergeJoinRelat
{
var rightIndex = field- mergeJoinRelation.Left.OutputLength;

rightEmit.Add(rightIndex);
rightEmit.Add(rightEmitToInternal[rightIndex]);
oldToNew.Add(field, replacementCounter);
replacementCounter += 1;
}
Expand Down
30 changes: 30 additions & 0 deletions tests/FlowtideDotNet.AcceptanceTests/JoinTests.cs
Original file line number Diff line number Diff line change
Expand Up @@ -207,5 +207,35 @@ from subcompany in gj.DefaultIfEmpty()
companyName = subcompany?.Name ?? default(string)
});
}

/// <summary>
/// Special case for optimizer
/// </summary>
/// <returns></returns>
[Fact]
public async Task JoinJoinWithPushdown()
{
GenerateData(100);
await StartStream(@"
INSERT INTO output
SELECT
u.userkey, c.name
FROM users u
LEFT JOIN companies c
ON trim(u.companyid) = trim(c.companyid)
LEFT JOIN companies c2
ON u.companyid = c2.companyid");
await WaitForUpdate();

AssertCurrentDataEqual(
from user in Users
join company in Companies on user.CompanyId equals company.CompanyId into gj
from subcompany in gj.DefaultIfEmpty()
select new
{
user.UserKey,
companyName = subcompany?.Name ?? default(string)
});
}
}
}

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