This adds support for infinity to the interval data type, using the
same input/output representation as the other date/time data types
that support infinity. This allows various arithmetic operations on
infinite dates, timestamps and intervals.
The new values are represented by setting all fields of the interval
to INT32/64_MIN for -infinity, and INT32/64_MAX for +infinity. This
ensures that they compare as less/greater than all other interval
values, without the need for any special-case comparison code.
Note that, since those 2 values were formerly accepted as legal finite
intervals, pg_upgrade and dump/restore from an old database will turn
them from finite to infinite intervals. That seems OK, since those
exact values should be extremely rare in practice, and they are
outside the documented range supported by the interval type, which
gives us a certain amount of leeway.
Bump catalog version.
Joseph Koshakow, Jian He, and Ashutosh Bapat, reviewed by me.
Discussion: https://postgr.es/m/CAAvxfHea4%2BsPybKK7agDYOMo9N-Z3J6ZXf3BOM79pFsFNcRjwA%40mail.gmail.com
When calculating distance for interval values, the code mostly mimicked
interval_mi, i.e. it built a new interval value for the difference.
That however does not work for sufficiently distant interval values,
when the difference overflows the interval range.
Instead, we can calculate the distance directly, without constructing
the intermediate (and unnecessary) interval value.
Backpatch to 14, where minmax-multi indexes were introduced.
Reported-by: Dean Rasheed
Reviewed-by: Ashutosh Bapat, Dean Rasheed
Backpatch-through: 14
Discussion: https://postgr.es/m/eef0ea8c-4aaa-8d0d-027f-58b1f35dd170@enterprisedb.com
Make sure that infinite values in date/timestamp columns are treated as
if in infinite distance. Infinite values should not be merged with other
values, leaving them as outliers. The code however returned distance 0
in this case, so that infinite values were merged first. While this does
not break the index (i.e. it still produces correct query results), it
may make it much less efficient.
We don't need explicit handling of infinite date/timestamp values when
calculating distances, because those values are represented as extreme
but regular values (e.g. INT64_MIN/MAX for the timestamp type).
We don't need an exact distance, just a value that is much larger than
distanced between regular values. With the added cast to double values,
we can simply subtract the values.
The regression test queries a value in the "gap" and checks the range
was properly eliminated by the BRIN index.
This only affects minmax-multi indexes on timestamp/date columns with
infinite values, which is not very common in practice. The affected
indexes may need to be rebuilt.
Backpatch to 14, where minmax-multi indexes were introduced.
Reported-by: Ashutosh Bapat
Reviewed-by: Ashutosh Bapat, Dean Rasheed
Backpatch-through: 14
Discussion: https://postgr.es/m/eef0ea8c-4aaa-8d0d-027f-58b1f35dd170@enterprisedb.com
When calculating the distance between date values, make sure to subtract
them in the right order, i.e. (larger - smaller).
The distance is used to determine which values to merge, and is expected
to be a positive value. The code unfortunately did the subtraction in
the opposite order, i.e. (smaller - larger), thus producing negative
values and merging values the most distant values first.
The resulting index is correct (i.e. produces correct results), but may
be significantly less efficient. This affects all minmax-multi indexes
on date columns.
Backpatch to 14, where minmax-multi indexes were introduced.
Reported-by: Ashutosh Bapat
Reviewed-by: Ashutosh Bapat, Dean Rasheed
Backpatch-through: 14
Discussion: https://postgr.es/m/eef0ea8c-4aaa-8d0d-027f-58b1f35dd170@enterprisedb.com
When calculating distances for timestamp values for BRIN minmax-multi
indexes, we need to be careful about overflows for extreme values. If
the value overflows into a negative value, the index may be inefficient.
The new regression test checks this for the timestamp type by adding a
table with enough values to force range compaction/merging. The values
are close to min/max, which means a risk of overflow.
Fixed by converting the int64 values to double first, before calculating
the distance. This prevents the overflow. We may lose some precision, of
course, but that's good enough. In the worst case we build a slightly
less efficient index, but for large distances this won't matter.
This only affects minmax-multi indexes on timestamp columns, with ranges
containing values sufficiently distant to cause an overflow. That seems
like a fairly rare case in practice.
Backpatch to 14, where minmax-multi indexes were introduced.
Reported-by: Ashutosh Bapat
Reviewed-by: Ashutosh Bapat, Dean Rasheed
Backpatch-through: 14
Discussion: https://postgr.es/m/eef0ea8c-4aaa-8d0d-027f-58b1f35dd170@enterprisedb.com
Per the code coverage report, the existing regression tests did not
exercice some a couple important BRIN minmax-multi code paths.
- The tests focused on testing planning with a range of scan key
strategies, but not the execution. Fixed by adding queries that
actually test query execution for both equality and inequality.
- All tests created indexes after inserting data, but this only
exercises the CREATE INDEX strategy that sees all values at once, not
incremental summary updates. The new tests flip the order and create
the index before adding data.
- The assert check(s) validating correctness of expanded ranges were
present only in the "union" code path, which is not covered by
regression tests at all (as it requires concurrency etc.). Fixed by
adding the asserts to a couple more places.
Reviewed-by: Heikki Linnakangas
Discussion: https://postgr.es/m/57020b2e-d9c9-9bc7-4892-b36d9bb07563%40enterprisedb.com
When calculating distance in brin_minmax_multi_distance_inet(), the
netmask was applied incorrectly. This results in (seemingly) incorrect
ordering of values, triggering an assert.
For builds without asserts this is mostly harmless - we may merge other
ranges, possibly resulting in slightly less efficient index. But it's
still correct and the greedy algorithm doesn't guarantee optimality
anyway.
Backpatch to 14, where minmax-multi indexes were introduced.
Reported by Dmitry Dolgov, investigation and fix by me.
Reported-by: Dmitry Dolgov
Backpatch-through: 14
Discussion: https://postgr.es/m/17774-c6f3e36dd4471e67@postgresql.org
Most of these calls were to generate some random data. These can be
replaced by appropriately adapted sha256() calls. To keep the diff
smaller, we wrap this into a helper function that produces the same
output format and length as the md5() call.
This will eventually allow these tests to pass in OpenSSL FIPS mode
(which does not allow MD5 use).
Similar work for other test suites will follow later.
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://www.postgresql.org/message-id/flat/dbbd927f-ef1f-c9a1-4ec6-c759778ac852@enterprisedb.com
When calculating distance between float4/float8 values, we need to be a
bit more careful about NaN values in order not to trigger assert. We
consider NaN values to be equal (distace 0.0) and in infinite distance
from all other values.
On builds without asserts, this issue is mostly harmless - the ranges
may be merged in less efficient order, but the index is still correct.
Per report from Andreas Seltenreich. Backpatch to 14, where this new
BRIN opclass was introduced.
Reported-by: Andreas Seltenreich
Discussion: https://postgr.es/m/87r1bw9ukm.fsf@credativ.de
Adds BRIN opclasses similar to the existing minmax, except that instead
of summarizing the page range into a single [min,max] range, the summary
consists of multiple ranges and/or points, allowing gaps. This allows
more efficient handling of data with poor correlation to physical
location within the table and/or outlier values, for which the regular
minmax opclassed tend to work poorly.
It's possible to specify the number of values kept for each page range,
either as a single point or an interval boundary.
CREATE TABLE t (a int);
CREATE INDEX ON t
USING brin (a int4_minmax_multi_ops(values_per_range=16));
When building the summary, the values are combined into intervals with
the goal to minimize the "covering" (sum of interval lengths), using a
support procedure computing distance between two values.
Bump catversion, due to various catalog changes.
Author: Tomas Vondra <tomas.vondra@postgresql.org>
Reviewed-by: Alvaro Herrera <alvherre@alvh.no-ip.org>
Reviewed-by: Alexander Korotkov <aekorotkov@gmail.com>
Reviewed-by: Sokolov Yura <y.sokolov@postgrespro.ru>
Reviewed-by: John Naylor <john.naylor@enterprisedb.com>
Discussion: https://postgr.es/m/c1138ead-7668-f0e1-0638-c3be3237e812@2ndquadrant.com
Discussion: https://postgr.es/m/5d78b774-7e9c-c94e-12cf-fef51cc89b1a%402ndquadrant.com
Robert Haas
Peter Eisentraut
Dean Rasheed
Tomas Vondra