- 18 Jan, 1999 1 commit
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Bruce Momjian authored
INTERSECT and EXCEPT is available for postgresql-v6.4! The patch against v6.4 is included at the end of the current text (in uuencoded form!) I also included the text of my Master's Thesis. (a postscript version). I hope that you find something of it useful and would be happy if parts of it find their way into the PostgreSQL documentation project (If so, tell me, then I send the sources of the document!) The contents of the document are: -) The first chapter might be of less interest as it gives only an overview on SQL. -) The second chapter gives a description on much of PostgreSQL's features (like user defined types etc. and how to use these features) -) The third chapter starts with an overview of PostgreSQL's internal structure with focus on the stages a query has to pass (i.e. parser, planner/optimizer, executor). Then a detailed description of the implementation of the Having clause and the Intersect/Except logic is given. Originally I worked on v6.3.2 but never found time enough to prepare and post a patch. Now I applied the changes to v6.4 to get Intersect and Except working with the new version. Chapter 3 of my documentation deals with the changes against v6.3.2, so keep that in mind when comparing the parts of the code printed there with the patched sources of v6.4. Here are some remarks on the patch. There are some things that have still to be done but at the moment I don't have time to do them myself. (I'm doing my military service at the moment) Sorry for that :-( -) I used a rewrite technique for the implementation of the Except/Intersect logic which rewrites the query to a semantically equivalent query before it is handed to the rewrite system (for views, rules etc.), planner, executor etc. -) In v6.3.2 the types of the attributes of two select statements connected by the UNION keyword had to match 100%. In v6.4 the types only need to be familiar (i.e. int and float can be mixed). Since this feature did not exist when I worked on Intersect/Except it does not work correctly for Except/Intersect queries WHEN USED IN COMBINATION WITH UNIONS! (i.e. sometimes the wrong type is used for the resulting table. This is because until now the types of the attributes of the first select statement have been used for the resulting table. When Intersects and/or Excepts are used in combination with Unions it might happen, that the first select statement of the original query appears at another position in the query which will be executed. The reason for this is the technique used for the implementation of Except/Intersect which does a query rewrite!) NOTE: It is NOT broken for pure UNION queries and pure INTERSECT/EXCEPT queries!!! -) I had to add the field intersect_clause to some data structures but did not find time to implement printfuncs for the new field. This does NOT break the debug modes but when an Except/Intersect is used the query debug output will be the already rewritten query. -) Massive changes to the grammar rules for SELECT and INSERT statements have been necessary (see comments in gram.y and documentation for deatails) in order to be able to use mixed queries like (SELECT ... UNION (SELECT ... EXCEPT SELECT)) INTERSECT SELECT...; -) When using UNION/EXCEPT/INTERSECT you will get: NOTICE: equal: "Don't know if nodes of type xxx are equal". I did not have time to add comparsion support for all the needed nodes, but the default behaviour of the function equal met my requirements. I did not dare to supress this message! That's the reason why the regression test for union will fail: These messages are also included in the union.out file! -) Somebody of you changed the union_planner() function for v6.4 (I copied the targetlist to new_tlist and that was removed and replaced by a cleanup of the original targetlist). These chnages violated some having queries executed against views so I changed it back again. I did not have time to examine the differences between the two versions but now it works :-) If you want to find out, try the file queries/view_having.sql on both versions and compare the results . Two queries won't produce a correct result with your version. regards Stefan
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- 14 Dec, 1998 1 commit
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Marc G. Fournier authored
Many more cleanups...
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- 04 Dec, 1998 1 commit
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Thomas G. Lockhart authored
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- 28 Oct, 1998 1 commit
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Bruce Momjian authored
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- 25 Sep, 1998 1 commit
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Thomas G. Lockhart authored
Remove _all_ PARSEDEBUG print statements.
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- 16 Sep, 1998 1 commit
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Thomas G. Lockhart authored
Check for a constraint if is_sequence is set and omit making a UNIQUE index if so, since the primary key will cover that for us.
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- 03 Sep, 1998 1 commit
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Thomas G. Lockhart authored
supplied by a DEFAULT clause. Enables INSERT INTO TABLE DEFAULT VALUES...
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- 01 Sep, 1998 2 commits
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Bruce Momjian authored
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Bruce Momjian authored
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- 26 Aug, 1998 2 commits
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Bruce Momjian authored
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Thomas G. Lockhart authored
and index name fields are pstrdup'd (copied) rather than reused.
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- 25 Aug, 1998 1 commit
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Thomas G. Lockhart authored
statements: - the table definition with a default clause referencing the sequence; - a CREATE SEQUENCE statement; - a UNIQUE constraint, which expands into a CREATE INDEX statement. This is not a perfect solution, since the sequence will remain even if the table is dropped. Also, there is no absolute protection on updating the sequence column.
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- 18 Aug, 1998 1 commit
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Marc G. Fournier authored
From: Jan Wieck <jwieck@debis.com> Hi, as proposed here comes the first patch for the query rewrite system. <for details, see archive dated Mon, 17 Aug 1998>
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- 20 Jul, 1998 2 commits
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Bruce Momjian authored
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Bruce Momjian authored
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- 19 Jul, 1998 1 commit
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Bruce Momjian authored
now. Here some tested features, (examples included in the patch): 1.1) Subselects in the having clause 1.2) Double nested subselects 1.3) Subselects used in the where clause and in the having clause simultaneously 1.4) Union Selects using having 1.5) Indexes on the base relations are used correctly 1.6) Unallowed Queries are prevented (e.g. qualifications in the having clause that belong to the where clause) 1.7) Insert into as select 2) Queries using the having clause on view relations also work but there are some restrictions: 2.1) Create View as Select ... Having ...; using base tables in the select 2.1.1) The Query rewrite system: 2.1.2) Why are only simple queries allowed against a view from 2.1) ? 2.2) Select ... from testview1, testview2, ... having...; 3) Bug in ExecMergeJoin ?? Regards Stefan
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- 29 May, 1998 1 commit
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Thomas G. Lockhart authored
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- 09 May, 1998 1 commit
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Thomas G. Lockhart authored
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- 31 Mar, 1998 1 commit
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Bruce Momjian authored
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- 30 Mar, 1998 2 commits
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Bruce Momjian authored
yyerror ones from bison. It also includes a few 'enhancements' to the C programming style (which are, of course, personal). The other patch removes the compilation of backend/lib/qsort.c, as qsort() is a standard function in stdlib.h and can be used any where else (and it is). It was only used in backend/optimizer/geqo/geqo_pool.c, backend/optimizer/path/predmig.c, and backend/storage/page/bufpage.c > > Some or all of these changes might not be appropriate for v6.3, since we > > are in beta testing and since they do not affect the current functionality. > > For those cases, how about submitting patches based on the final v6.3 > > release? There's more to come. Please review these patches. I ran the regression tests and they only failed where this was expected (random, geo, etc). Cheers, Jeroen
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Bruce Momjian authored
sequential scans! (I think it will also work with hash, index, etc but I did not check it out! I made some High level changes which should work for all access methods, but maybe I'm wrong. Please let me know.) Now it is possible to make queries like: select s.sname, max(p.pid), min(p.pid) from part p, supplier s where s.sid=p.sid group by s.sname having max(pid)=6 and min(pid)=1 or avg(pid)=4; Having does not work yet for queries that contain a subselect statement in the Having clause, I'll try to fix this in the next days. If there are some bugs, please let me know, I'll start to read the mailinglists now! Now here is the patch against the original 6.3 version (no snapshot!!): Stefan
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- 26 Feb, 1998 1 commit
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Bruce Momjian authored
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- 10 Feb, 1998 1 commit
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Bruce Momjian authored
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- 06 Feb, 1998 1 commit
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Bruce Momjian authored
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- 20 Jan, 1998 2 commits
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Bruce Momjian authored
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Bruce Momjian authored
Add lock to i386 asm.
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- 19 Jan, 1998 1 commit
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Bruce Momjian authored
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- 15 Jan, 1998 1 commit
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Bruce Momjian authored
Pass List* of Aggregs into executor, and create needed array there. No longer need to double-processs Aggregs with second copy in Query. Fix crash when doing: select sum(x+1) from test where 1 > 0;
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- 11 Jan, 1998 1 commit
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Bruce Momjian authored
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- 10 Jan, 1998 1 commit
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Bruce Momjian authored
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- 09 Jan, 1998 1 commit
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Bruce Momjian authored
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- 05 Jan, 1998 1 commit
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Bruce Momjian authored
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- 29 Dec, 1997 3 commits
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Bruce Momjian authored
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Bruce Momjian authored
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Bruce Momjian authored
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- 27 Dec, 1997 1 commit
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Bruce Momjian authored
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- 24 Dec, 1997 1 commit
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Bruce Momjian authored
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- 23 Dec, 1997 1 commit
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Thomas G. Lockhart authored
Add a few lines of test code playing with the unique flag for unions. Does not do much helpful yet.
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- 16 Dec, 1997 1 commit
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Thomas G. Lockhart authored
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- 09 Dec, 1997 1 commit
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Thomas G. Lockhart authored
Check for duplicate implicit index names and generate unique names.
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