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author | Marc G. Fournier <scrappy@hub.org> | 1996-08-26 20:02:12 +0000 |
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committer | Marc G. Fournier <scrappy@hub.org> | 1996-08-26 20:02:12 +0000 |
commit | e78fe652f48f9dbb67a21f616741e7b446204cbe (patch) | |
tree | dcf94f3d8d6b1ff4923486c24e15ace811e82d38 /src/backend/access/gist/giststrat.c | |
parent | 2fd6061e1c8c91f3d1398826ddfddbcefce477e8 (diff) | |
download | postgresql-e78fe652f48f9dbb67a21f616741e7b446204cbe.tar.gz |
Oops, thanks to Dan McGuirk for pointing out that I missed part of
the commit :(
Here's the rest of the GiST code thta was missing...
Diffstat (limited to 'src/backend/access/gist/giststrat.c')
-rw-r--r-- | src/backend/access/gist/giststrat.c | 119 |
1 files changed, 119 insertions, 0 deletions
diff --git a/src/backend/access/gist/giststrat.c b/src/backend/access/gist/giststrat.c new file mode 100644 index 0000000000..1dea1946d9 --- /dev/null +++ b/src/backend/access/gist/giststrat.c @@ -0,0 +1,119 @@ +/*------------------------------------------------------------------------- + * + * giststrat.c-- + * strategy map data for GiSTs. + * + * Copyright (c) 1994, Regents of the University of California + * + * + * IDENTIFICATION + * /usr/local/devel/pglite/cvs/src/backend/access/gist/giststrat.c,v 1.4 1995/06/14 00:10:05 jolly Exp + * + *------------------------------------------------------------------------- + */ +#include "c.h" + +#include "utils/rel.h" + +#include "storage/bufmgr.h" +#include "storage/bufpage.h" + +#include "access/istrat.h" +#include "access/gist.h" + +/* + * Note: negate, commute, and negatecommute all assume that operators are + * ordered as follows in the strategy map: + * + * contains, contained-by + * + * The negate, commute, and negatecommute arrays are used by the planner + * to plan indexed scans over data that appears in the qualificiation in + * a boolean negation, or whose operands appear in the wrong order. For + * example, if the operator "<%" means "contains", and the user says + * + * where not rel.box <% "(10,10,20,20)"::box + * + * the planner can plan an index scan by noting that GiST indices have + * an operator in their operator class for negating <%. + * + * Similarly, if the user says something like + * + * where "(10,10,20,20)"::box <% rel.box + * + * the planner can see that the GiST index on rel.box has an operator in + * its opclass for commuting <%, and plan the scan using that operator. + * This added complexity in the access methods makes the planner a lot easier + * to write. + */ + +/* if a op b, what operator tells us if (not a op b)? */ +static StrategyNumber GISTNegate[GISTNStrategies] = { + InvalidStrategy, + InvalidStrategy, + InvalidStrategy + }; + +/* if a op_1 b, what is the operator op_2 such that b op_2 a? */ +static StrategyNumber GISTCommute[GISTNStrategies] = { + InvalidStrategy, + InvalidStrategy, + InvalidStrategy + }; + +/* if a op_1 b, what is the operator op_2 such that (b !op_2 a)? */ +static StrategyNumber GISTNegateCommute[GISTNStrategies] = { + InvalidStrategy, + InvalidStrategy, + InvalidStrategy + }; + +/* + * GiSTs do not currently support TermData (see rtree/rtstrat.c for + * discussion of + * TermData) -- such logic must be encoded in the user's Consistent function. + */ + +/* + * If you were sufficiently attentive to detail, you would go through + * the ExpressionData pain above for every one of the strategies + * we defined. I am not. Now we declare the StrategyEvaluationData + * structure that gets shipped around to help the planner and the access + * method decide what sort of scan it should do, based on (a) what the + * user asked for, (b) what operators are defined for a particular opclass, + * and (c) the reams of information we supplied above. + * + * The idea of all of this initialized data is to make life easier on the + * user when he defines a new operator class to use this access method. + * By filling in all the data, we let him get away with leaving holes in his + * operator class, and still let him use the index. The added complexity + * in the access methods just isn't worth the trouble, though. + */ + +static StrategyEvaluationData GISTEvaluationData = { + GISTNStrategies, /* # of strategies */ + (StrategyTransformMap) GISTNegate, /* how to do (not qual) */ + (StrategyTransformMap) GISTCommute, /* how to swap operands */ + (StrategyTransformMap) GISTNegateCommute, /* how to do both */ + NULL +}; + +StrategyNumber +RelationGetGISTStrategy(Relation r, + AttrNumber attnum, + RegProcedure proc) +{ + return (RelationGetStrategy(r, attnum, &GISTEvaluationData, proc)); +} + +bool +RelationInvokeGISTStrategy(Relation r, + AttrNumber attnum, + StrategyNumber s, + Datum left, + Datum right) +{ + return (RelationInvokeStrategy(r, &GISTEvaluationData, attnum, s, + left, right)); +} + |