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Introduction
The PostgreSQL regression tests are a comprehensive set of tests for the
SQL implementation embedded in PostgreSQL developed by Jolly Chen and
Andrew Yu. It tests standard SQL operations as well as the extensibility
capabilities of PostgreSQL.
These tests have recently been revised by Marc Fournier and others to
become current for PostgreSQL v6.1. The tests are now packaged as
functional units and should be easier to run and easier to interpret.
Some properly installed and fully functional PostgreSQL installations
can fail these regression tests due to artifacts of the genetic optimizer.
See the v6.1-specific release notes in this document for further details.
Preparation
The regression test is invoked by the 'make' command which compiles
a 'c' program with PostgreSQL extension functions into a shared library
in the current directory. Localized shell scripts are also created in
the current directory. The output file templates are massaged into the
./expected/*.out files. The localization replaces macros in the source
files with absolute pathnames and user names.
The postmaster should be invoked with the system time zone set for
Berkeley, California. On some systems, this can be accomplished by
setting the TZ environment variable before starting the postmaster
(for csh/bash; use set/export for some other shells):
setenv TZ PST8PDT7,M04.01.0,M10.05.03
/usr/local/pgsql/bin/postmaster -s
Directory Layout
input/ .... .source files that are converted using 'make all' into
some of the .sql files in the 'sql' subdirectory
output/ ... .source files that are converted using 'make all' into
.out files in the 'expected' subdirectory
sql/ ...... .sql files used to perform the regression tests
expected/ . .out files that represent what we *expect* the results to
look like
results/ .. .out files that represent what the results *actually* look
like. Also used as temporary storage for table copy testing.
Running the regression test
If you have prevously invoked the regression test, clean up the
working directory with:
make clean
The regression test is invoked with the command:
make all runtest
Normally, the regression test should be run as the pg_superuser as the
'src/test/regress' directory and sub-directories are owned by the
pg_superuser. If you run the regression test as another user the
'src/test/regress' directory tree should be writeable to that user.
Comparing expected/actual output
The results are in the files in the ./results directory. These
results can be compared with results in the ./expected directory
using 'diff'. The files might not compare exactly. The following
paragraphs attempt to explain the differences.
OID differences
There are several places where PostgreSQL OID (object identifiers) appear
in 'regress.out'. OID's are unique 32-bit integers which are generated
by the PostgreSQL backend whenever a table row is inserted or updated.
If you run the regression test on a non-virgin database or run it multiple
times, the OID's reported will have different values.
The following SQL statements in 'misc.out' have shown this behavior:
QUERY: SELECT user_relns() AS user_relns ORDER BY user_relns;
The 'a,523676' row is composed from an OID.
DATE/TIME differences
On many supported platforms, you can force PostgreSQL to believe that it
is running in the same time zone as Berkeley, California. See details in
the section on how to run the regression tests.
If you do not explicitly set your time zone environment to PST/PDT, then
most of the date and time results will reflect your local time zone and
will fail the regression testing.
FLOATING POINT differences
Some of the tests involve computing 64-bit (FLOAT8) number from table
columns. Differences in results involving mathematical functions of
FLOAT8 columns have been observed. These differences occur where
different operating systems are used on the same platform ie:
BSDI and SOLARIS on Intel/86, and where the same operating system is
used used on different platforms, ie: SOLARIS on SPARC and Intel/86.
Human eyeball comparison is needed to determine the real significance
of these differences which are usually 10 places to the right of
the decimal point.
POLYGON differences
Several of the tests involve operations on geographic date about the
Oakland/Berkley CA street map. The map data is expressed as polygons
whose vertices are represented as pairs of FLOAT8 numbers (decimal
latitude and longitude). Initially, some tables are created and
loaded with geographic data, then some views are created which join
two tables using the polygon intersection operator (##), then a select
is done on the view.
When comparing the results from different platforms, differences occur
in the 2nd or 3rd place to the right of the decimal point. The SQL
statements where these problems occur are the folowing:
QUERY: SELECT * from street;
QUERY: SELECT * from iexit;
Random differences
There is at least one test case in random.out which is intended to produce
random results. This causes random to fail the regression testing.
Typing "diff results/random.out expected/random.out" should produce only
one or a few lines of differences for this reason, but other floating
point differences on dissimilar architectures might cause many more
differences. See the release notes below.
The 'expected' files
The ./expected/*.out files were adapted from the original monolithic
'expected.input' file provided by Jolly Chen et al. Newer versions of these
files generated on various development machines have been substituted after
careful (?) inspection. Many of the development machines are running a
Unix OS variant (FreeBSD, Linux, etc) on Ix86 hardware.
The original 'expected.input' file was created on a SPARC Solaris 2.4
system using the 'postgres5-1.02a5.tar.gz' source tree. It was compared
with a file created on an I386 Solaris 2.4 system and the differences
were only in the floating point polygons in the 3rd digit to the right
of the decimal point. (see below)
The original 'sample.regress.out' file was from the postgres-1.01 release
constructed by Jolly Chen and is included here for reference. It may
have been created on a DEC ALPHA machine as the 'Makefile.global'
in the postgres-1.01 release has PORTNAME=alpha.
Current release notes (Thomas.Lockhart@jpl.nasa.gov)
The regression tests have been adapted and extensively modified for the
v6.1 release of PostgreSQL.
Three new data types (datetime, timespan, and circle) have been added to
the native set of PostgreSQL types. Points, boxes, paths, and polygons
have had their output formats improved, but the old-style input formats
are accepted by v6.1. The source data files have not been updated to the
new formats, but should be for the next release. The polygon output in
misc.out has only been spot-checked for correctness relative to the
original regression output.
PostgreSQL v6.1 introduces a new, alternate optimizer which uses "genetic"
algorithms. These algorithms introduce a random behavior in the ordering
of query results when the query contains multiple qualifiers or multiple
tables (giving the optimizer a choice on order of evaluation). Several
regression tests have been modified to explicitly order the results, and
hence are insensitive to optimizer choices. A few regression tests are
for data types which are inherently unordered (e.g. points and time
intervals) and tests involving those types are explicitly bracketed with
"set geqo to 'off'" and "reset geqo".
The interpretation of array specifiers (the curly braces around atomic
values) appears to have changed sometime after the original regression
tests were generated. The current ./expected/*.out files reflect this
new interpretation, which may not be correct!
The float8 regression test fails on at least some platforms. This is due
to differences in implementations of pow() and exp() and the signaling
mechanisms used for overflow and underflow conditions.
The "random" results in the random test do not seem to produce random
results on my test machine (Linux/gcc/i686).
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