[SPARK-9518] [SQL] cleanup generated UnsafeRowJoiner and fix bug #7892
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| @@ -91,8 +92,9 @@ class GenerateUnsafeRowJoinerBitsetSuite extends SparkFunSuite { | |||
| private def createUnsafeRow(numFields: Int): UnsafeRow = { | |||
| val row = new UnsafeRow | |||
| val sizeInBytes = numFields * 8 + ((numFields + 63) / 64) * 8 | |||
| val buf = new Array[Byte](sizeInBytes) | |||
| row.pointTo(buf, numFields, sizeInBytes) | |||
| val offset = numFields * 8 | |||
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this is added to explicitly test adding some offset right?
if that's the case, why make it numFields * 8?
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Just want to make it randomly, also aligned with word.
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ok maybe say that in the comment - right now this number doesn't feel random; it feels as if there is an explicit choice here :)
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Test build #39529 has finished for PR 7892 at commit
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I've merged this. Will fix my own comments during merging. |
asfgit
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…enerateUnsafeRowJoiner ## What changes were proposed in this pull request? This PR fixes a longstanding correctness bug in `GenerateUnsafeRowJoiner`. This class was introduced in #7821 (July 2015 / Spark 1.5.0+) and is used to combine pairs of UnsafeRows in TungstenAggregationIterator, CartesianProductExec, and AppendColumns. ### Bugs fixed by this patch 1. **Incorrect combining of null-tracking bitmaps**: when concatenating two UnsafeRows, the implementation "Concatenate the two bitsets together into a single one, taking padding into account". If one row has no columns then it has a bitset size of 0, but the code was incorrectly assuming that if the left row had a non-zero number of fields then the right row would also have at least one field, so it was copying invalid bytes and and treating them as part of the bitset. I'm not sure whether this bug was also present in the original implementation or whether it was introduced in #7892 (which fixed another bug in this code). 2. **Incorrect updating of data offsets for null variable-length fields**: after updating the bitsets and copying fixed-length and variable-length data, we need to perform adjustments to the offsets pointing the start of variable length fields's data. The existing code was _conditionally_ adding a fixed offset to correct for the new length of the combined row, but it is unsafe to do this if the variable-length field has a null value: we always represent nulls by storing `0` in the fixed-length slot, but this code was incorrectly incrementing those values. This bug was present since the original version of `GenerateUnsafeRowJoiner`. ### Why this bug remained latent for so long The PR which introduced `GenerateUnsafeRowJoiner` features several randomized tests, including tests of the cases where one side of the join has no fields and where string-valued fields are null. However, the existing assertions were too weak to uncover this bug: - If a null field has a non-zero value in its fixed-length data slot then this will not cause problems for field accesses because the null-tracking bitmap should still be correct and we will not try to use the incorrect offset for anything. - If the null tracking bitmap is corrupted by joining against a row with no fields then the corruption occurs in field numbers past the actual field numbers contained in the row. Thus valid `isNullAt()` calls will not read the incorrectly-set bits. The existing `GenerateUnsafeRowJoinerSuite` tests only exercised `.get()` and `isNullAt()`, but didn't actually check the UnsafeRows for bit-for-bit equality, preventing these bugs from failing assertions. It turns out that there was even a [GenerateUnsafeRowJoinerBitsetSuite](https://github.com/apache/spark/blob/03377d2522776267a07b7d6ae9bddf79a4e0f516/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/codegen/GenerateUnsafeRowJoinerBitsetSuite.scala) but it looks like it also didn't catch this problem because it only tested the bitsets in an end-to-end fashion by accessing them through the `UnsafeRow` interface instead of actually comparing the bitsets' bytes. ### Impact of these bugs - This bug will cause `equals()` and `hashCode()` to be incorrect for these rows, which will be problematic in case`GenerateUnsafeRowJoiner`'s results are used as join or grouping keys. - Chained / repeated invocations of `GenerateUnsafeRowJoiner` may result in reads from invalid null bitmap positions causing fields to incorrectly become NULL (see the end-to-end example below). - It looks like this generally only happens in `CartesianProductExec`, which our query optimizer often avoids executing (usually we try to plan a `BroadcastNestedLoopJoin` instead). ### End-to-end test case demonstrating the problem The following query demonstrates how this bug may result in incorrect query results: ```sql set spark.sql.autoBroadcastJoinThreshold=-1; -- Needed to trigger CartesianProductExec create table a as select * from values 1; create table b as select * from values 2; SELECT t3.col1, t1.col1 FROM a t1 CROSS JOIN b t2 CROSS JOIN b t3 ``` This should return `(2, 1)` but instead was returning `(null, 1)`. Column pruning ends up trimming off all columns from `t2`, so when `t2` joins with another table this triggers the bitmap-copying bug. This incorrect bitmap is subsequently copied again when performing the final join, causing the final output to have an incorrectly-set null bit for the first field. ## How was this patch tested? Strengthened the assertions in existing tests in GenerateUnsafeRowJoinerSuite. Also verified that the end-to-end test case which uncovered this now passes. Author: Josh Rosen <joshrosen@databricks.com> Closes #20181 from JoshRosen/SPARK-22984-fix-generate-unsaferow-joiner-bitmap-bugs.
asfgit
pushed a commit
that referenced
this pull request
Jan 9, 2018
…enerateUnsafeRowJoiner ## What changes were proposed in this pull request? This PR fixes a longstanding correctness bug in `GenerateUnsafeRowJoiner`. This class was introduced in #7821 (July 2015 / Spark 1.5.0+) and is used to combine pairs of UnsafeRows in TungstenAggregationIterator, CartesianProductExec, and AppendColumns. ### Bugs fixed by this patch 1. **Incorrect combining of null-tracking bitmaps**: when concatenating two UnsafeRows, the implementation "Concatenate the two bitsets together into a single one, taking padding into account". If one row has no columns then it has a bitset size of 0, but the code was incorrectly assuming that if the left row had a non-zero number of fields then the right row would also have at least one field, so it was copying invalid bytes and and treating them as part of the bitset. I'm not sure whether this bug was also present in the original implementation or whether it was introduced in #7892 (which fixed another bug in this code). 2. **Incorrect updating of data offsets for null variable-length fields**: after updating the bitsets and copying fixed-length and variable-length data, we need to perform adjustments to the offsets pointing the start of variable length fields's data. The existing code was _conditionally_ adding a fixed offset to correct for the new length of the combined row, but it is unsafe to do this if the variable-length field has a null value: we always represent nulls by storing `0` in the fixed-length slot, but this code was incorrectly incrementing those values. This bug was present since the original version of `GenerateUnsafeRowJoiner`. ### Why this bug remained latent for so long The PR which introduced `GenerateUnsafeRowJoiner` features several randomized tests, including tests of the cases where one side of the join has no fields and where string-valued fields are null. However, the existing assertions were too weak to uncover this bug: - If a null field has a non-zero value in its fixed-length data slot then this will not cause problems for field accesses because the null-tracking bitmap should still be correct and we will not try to use the incorrect offset for anything. - If the null tracking bitmap is corrupted by joining against a row with no fields then the corruption occurs in field numbers past the actual field numbers contained in the row. Thus valid `isNullAt()` calls will not read the incorrectly-set bits. The existing `GenerateUnsafeRowJoinerSuite` tests only exercised `.get()` and `isNullAt()`, but didn't actually check the UnsafeRows for bit-for-bit equality, preventing these bugs from failing assertions. It turns out that there was even a [GenerateUnsafeRowJoinerBitsetSuite](https://github.com/apache/spark/blob/03377d2522776267a07b7d6ae9bddf79a4e0f516/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/codegen/GenerateUnsafeRowJoinerBitsetSuite.scala) but it looks like it also didn't catch this problem because it only tested the bitsets in an end-to-end fashion by accessing them through the `UnsafeRow` interface instead of actually comparing the bitsets' bytes. ### Impact of these bugs - This bug will cause `equals()` and `hashCode()` to be incorrect for these rows, which will be problematic in case`GenerateUnsafeRowJoiner`'s results are used as join or grouping keys. - Chained / repeated invocations of `GenerateUnsafeRowJoiner` may result in reads from invalid null bitmap positions causing fields to incorrectly become NULL (see the end-to-end example below). - It looks like this generally only happens in `CartesianProductExec`, which our query optimizer often avoids executing (usually we try to plan a `BroadcastNestedLoopJoin` instead). ### End-to-end test case demonstrating the problem The following query demonstrates how this bug may result in incorrect query results: ```sql set spark.sql.autoBroadcastJoinThreshold=-1; -- Needed to trigger CartesianProductExec create table a as select * from values 1; create table b as select * from values 2; SELECT t3.col1, t1.col1 FROM a t1 CROSS JOIN b t2 CROSS JOIN b t3 ``` This should return `(2, 1)` but instead was returning `(null, 1)`. Column pruning ends up trimming off all columns from `t2`, so when `t2` joins with another table this triggers the bitmap-copying bug. This incorrect bitmap is subsequently copied again when performing the final join, causing the final output to have an incorrectly-set null bit for the first field. ## How was this patch tested? Strengthened the assertions in existing tests in GenerateUnsafeRowJoinerSuite. Also verified that the end-to-end test case which uncovered this now passes. Author: Josh Rosen <joshrosen@databricks.com> Closes #20181 from JoshRosen/SPARK-22984-fix-generate-unsaferow-joiner-bitmap-bugs. (cherry picked from commit f20131d) Signed-off-by: Wenchen Fan <wenchen@databricks.com>
asfgit
pushed a commit
that referenced
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Jan 9, 2018
…enerateUnsafeRowJoiner ## What changes were proposed in this pull request? This PR fixes a longstanding correctness bug in `GenerateUnsafeRowJoiner`. This class was introduced in #7821 (July 2015 / Spark 1.5.0+) and is used to combine pairs of UnsafeRows in TungstenAggregationIterator, CartesianProductExec, and AppendColumns. ### Bugs fixed by this patch 1. **Incorrect combining of null-tracking bitmaps**: when concatenating two UnsafeRows, the implementation "Concatenate the two bitsets together into a single one, taking padding into account". If one row has no columns then it has a bitset size of 0, but the code was incorrectly assuming that if the left row had a non-zero number of fields then the right row would also have at least one field, so it was copying invalid bytes and and treating them as part of the bitset. I'm not sure whether this bug was also present in the original implementation or whether it was introduced in #7892 (which fixed another bug in this code). 2. **Incorrect updating of data offsets for null variable-length fields**: after updating the bitsets and copying fixed-length and variable-length data, we need to perform adjustments to the offsets pointing the start of variable length fields's data. The existing code was _conditionally_ adding a fixed offset to correct for the new length of the combined row, but it is unsafe to do this if the variable-length field has a null value: we always represent nulls by storing `0` in the fixed-length slot, but this code was incorrectly incrementing those values. This bug was present since the original version of `GenerateUnsafeRowJoiner`. ### Why this bug remained latent for so long The PR which introduced `GenerateUnsafeRowJoiner` features several randomized tests, including tests of the cases where one side of the join has no fields and where string-valued fields are null. However, the existing assertions were too weak to uncover this bug: - If a null field has a non-zero value in its fixed-length data slot then this will not cause problems for field accesses because the null-tracking bitmap should still be correct and we will not try to use the incorrect offset for anything. - If the null tracking bitmap is corrupted by joining against a row with no fields then the corruption occurs in field numbers past the actual field numbers contained in the row. Thus valid `isNullAt()` calls will not read the incorrectly-set bits. The existing `GenerateUnsafeRowJoinerSuite` tests only exercised `.get()` and `isNullAt()`, but didn't actually check the UnsafeRows for bit-for-bit equality, preventing these bugs from failing assertions. It turns out that there was even a [GenerateUnsafeRowJoinerBitsetSuite](https://github.com/apache/spark/blob/03377d2522776267a07b7d6ae9bddf79a4e0f516/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/codegen/GenerateUnsafeRowJoinerBitsetSuite.scala) but it looks like it also didn't catch this problem because it only tested the bitsets in an end-to-end fashion by accessing them through the `UnsafeRow` interface instead of actually comparing the bitsets' bytes. ### Impact of these bugs - This bug will cause `equals()` and `hashCode()` to be incorrect for these rows, which will be problematic in case`GenerateUnsafeRowJoiner`'s results are used as join or grouping keys. - Chained / repeated invocations of `GenerateUnsafeRowJoiner` may result in reads from invalid null bitmap positions causing fields to incorrectly become NULL (see the end-to-end example below). - It looks like this generally only happens in `CartesianProductExec`, which our query optimizer often avoids executing (usually we try to plan a `BroadcastNestedLoopJoin` instead). ### End-to-end test case demonstrating the problem The following query demonstrates how this bug may result in incorrect query results: ```sql set spark.sql.autoBroadcastJoinThreshold=-1; -- Needed to trigger CartesianProductExec create table a as select * from values 1; create table b as select * from values 2; SELECT t3.col1, t1.col1 FROM a t1 CROSS JOIN b t2 CROSS JOIN b t3 ``` This should return `(2, 1)` but instead was returning `(null, 1)`. Column pruning ends up trimming off all columns from `t2`, so when `t2` joins with another table this triggers the bitmap-copying bug. This incorrect bitmap is subsequently copied again when performing the final join, causing the final output to have an incorrectly-set null bit for the first field. ## How was this patch tested? Strengthened the assertions in existing tests in GenerateUnsafeRowJoinerSuite. Also verified that the end-to-end test case which uncovered this now passes. Author: Josh Rosen <joshrosen@databricks.com> Closes #20181 from JoshRosen/SPARK-22984-fix-generate-unsaferow-joiner-bitmap-bugs. (cherry picked from commit f20131d) Signed-off-by: Wenchen Fan <wenchen@databricks.com>
MatthewRBruce
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Jul 31, 2018
…enerateUnsafeRowJoiner ## What changes were proposed in this pull request? This PR fixes a longstanding correctness bug in `GenerateUnsafeRowJoiner`. This class was introduced in apache#7821 (July 2015 / Spark 1.5.0+) and is used to combine pairs of UnsafeRows in TungstenAggregationIterator, CartesianProductExec, and AppendColumns. ### Bugs fixed by this patch 1. **Incorrect combining of null-tracking bitmaps**: when concatenating two UnsafeRows, the implementation "Concatenate the two bitsets together into a single one, taking padding into account". If one row has no columns then it has a bitset size of 0, but the code was incorrectly assuming that if the left row had a non-zero number of fields then the right row would also have at least one field, so it was copying invalid bytes and and treating them as part of the bitset. I'm not sure whether this bug was also present in the original implementation or whether it was introduced in apache#7892 (which fixed another bug in this code). 2. **Incorrect updating of data offsets for null variable-length fields**: after updating the bitsets and copying fixed-length and variable-length data, we need to perform adjustments to the offsets pointing the start of variable length fields's data. The existing code was _conditionally_ adding a fixed offset to correct for the new length of the combined row, but it is unsafe to do this if the variable-length field has a null value: we always represent nulls by storing `0` in the fixed-length slot, but this code was incorrectly incrementing those values. This bug was present since the original version of `GenerateUnsafeRowJoiner`. ### Why this bug remained latent for so long The PR which introduced `GenerateUnsafeRowJoiner` features several randomized tests, including tests of the cases where one side of the join has no fields and where string-valued fields are null. However, the existing assertions were too weak to uncover this bug: - If a null field has a non-zero value in its fixed-length data slot then this will not cause problems for field accesses because the null-tracking bitmap should still be correct and we will not try to use the incorrect offset for anything. - If the null tracking bitmap is corrupted by joining against a row with no fields then the corruption occurs in field numbers past the actual field numbers contained in the row. Thus valid `isNullAt()` calls will not read the incorrectly-set bits. The existing `GenerateUnsafeRowJoinerSuite` tests only exercised `.get()` and `isNullAt()`, but didn't actually check the UnsafeRows for bit-for-bit equality, preventing these bugs from failing assertions. It turns out that there was even a [GenerateUnsafeRowJoinerBitsetSuite](https://github.com/apache/spark/blob/03377d2522776267a07b7d6ae9bddf79a4e0f516/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/codegen/GenerateUnsafeRowJoinerBitsetSuite.scala) but it looks like it also didn't catch this problem because it only tested the bitsets in an end-to-end fashion by accessing them through the `UnsafeRow` interface instead of actually comparing the bitsets' bytes. ### Impact of these bugs - This bug will cause `equals()` and `hashCode()` to be incorrect for these rows, which will be problematic in case`GenerateUnsafeRowJoiner`'s results are used as join or grouping keys. - Chained / repeated invocations of `GenerateUnsafeRowJoiner` may result in reads from invalid null bitmap positions causing fields to incorrectly become NULL (see the end-to-end example below). - It looks like this generally only happens in `CartesianProductExec`, which our query optimizer often avoids executing (usually we try to plan a `BroadcastNestedLoopJoin` instead). ### End-to-end test case demonstrating the problem The following query demonstrates how this bug may result in incorrect query results: ```sql set spark.sql.autoBroadcastJoinThreshold=-1; -- Needed to trigger CartesianProductExec create table a as select * from values 1; create table b as select * from values 2; SELECT t3.col1, t1.col1 FROM a t1 CROSS JOIN b t2 CROSS JOIN b t3 ``` This should return `(2, 1)` but instead was returning `(null, 1)`. Column pruning ends up trimming off all columns from `t2`, so when `t2` joins with another table this triggers the bitmap-copying bug. This incorrect bitmap is subsequently copied again when performing the final join, causing the final output to have an incorrectly-set null bit for the first field. ## How was this patch tested? Strengthened the assertions in existing tests in GenerateUnsafeRowJoinerSuite. Also verified that the end-to-end test case which uncovered this now passes. Author: Josh Rosen <joshrosen@databricks.com> Closes apache#20181 from JoshRosen/SPARK-22984-fix-generate-unsaferow-joiner-bitmap-bugs. (cherry picked from commit f20131d) Signed-off-by: Wenchen Fan <wenchen@databricks.com>
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Currently, when copy the bitsets, we didn't consider that the row1 may not sit in the beginning of byte array.
cc @rxin