[SQL] Add functions for binary strings #1264
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* substring, overlay, octet_length, position Signed-off-by: Abhinav Gyawali <22275402+abhizer@users.noreply.github.com>
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...er/SQL-compiler/src/main/java/org/dbsp/sqlCompiler/compiler/frontend/ExpressionCompiler.java
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docs/sql/binary.md
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| <td><code>SUBSTRING</code>(binary FROM integer)</td> | ||
| <td>Generate a substring of binary starting at the given point. If the start position integer is negative, the substring starts at the position 0</td> |
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point = offset in bytes.
Are you sure about 0? Usually negative means that it's interpreted from the end.
Moverover, SQL offsets usually start at 1.
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Postgres doesn't allow indexing with negative numbers, so that's what we do here.
And yeah, it should be 1 instead of 0 in terms of SQL.
docs/sql/binary.md
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| <td><code>SUBSTRING</code>(binary FROM integer1 FOR integer2)</td> | ||
| <td>Generate a substring of binary starting at the given point with a given length. If the start position integer is negative, the substring starts at the position 0</td> |
docs/sql/binary.md
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| <td><code>OVERLAY</code>(binary1 PLACING binary2 FROM integer [ FOR integer2 ])</td> | ||
| <td>Generate a binary string that replaces substring of binary1 with binary2. If the start position integer is negative, the new string will contain binary2 in position 0</td> |
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what if the FOR size is smaller than the binary2 size?
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If FOR size is smaller than binary2 size, it still gets replaced by the entire binary2.
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| @Test | ||
| public void testOctetLength() { |
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are there postgres tests with these functions?
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Can we steal these too?
They can be part of a separate PR.
| public void testSubstring() { | ||
| this.qs( | ||
| """ | ||
| SELECT substring(x'123456', 0); |
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I suspect that substring(..., 1) will generate the same result.
Then it means that values below 1 are treated as 1.
...piler/SQL-compiler/src/test/java/org/dbsp/sqlCompiler/compiler/sql/mysql/VarbinaryTests.java
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Signed-off-by: Abhinav Gyawali <22275402+abhizer@users.noreply.github.com>
Signed-off-by: Mihai Budiu <mbudiu@gmail.com>
Is this a user-visible change (yes/no): yes (updates the docs)
#1262