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https://issues.apache.org/jira/browse/CALCITE-2818?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16788244#comment-16788244
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Andrei Sereda commented on CALCITE-2818:
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[~julianhyde] While reviewing this PR I have noticed that {{extract}} function
has different semantics depending on vendor.
{code:sql}
extract(millisecond from TIMESTAMP '1969-12-31 21:13:17.357')
{code}
Will return {{357}} in Oracle and SQL Server but {{17357}} in Postgres.
Do you think implementation should be different depending on current dialect ?
This is a separate discussion not related to current PR.
> EXTRACT returns wrong results for DATE and TIMESTAMP values before epoch
> ------------------------------------------------------------------------
>
> Key: CALCITE-2818
> URL: https://issues.apache.org/jira/browse/CALCITE-2818
> Project: Calcite
> Issue Type: Bug
> Reporter: Mickaël Sauvée
> Priority: Major
> Labels: easyfix, pull-request-available
> Time Spent: 1h 50m
> Remaining Estimate: 0h
>
> Implementation of Extract (ExtractImplementor) returns wrong result for dates
> before Epoch.
> Computation is based on Java modulo that have a certain behavior on negative
> number.
> For extracting hour, minutes and seconds, the computation is wrong.
> Here is an example on hour extract with the date 30-12-1969T21:13:20+0 is
> -100 000 000 in milliseconds relative to unix Epoch.
> (-100 000 000 % 86 400 000) / 3 600 000 = -3,77 , so 3 hour is returned, and
> it should be 21.
> For negative input value, it is required to add unit.multiplier.longValue()
> (ie. 8 640 000 in hour case) to the value before dividing it.
> You can use this test (SqlOperatorBaseTest.java):
>
> {code:java}
> @Test public void testExtractWithDatesBeforeUnixEpoch() {
> tester.checkScalar(
> "extract(hour from TIMESTAMP '1969-12-31 21:13:20')",
> "21",
> "BIGINT NOT NULL");
> }{code}
>
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