From c29c578908dc0271eeb13a4014e54bff07a29c05 Mon Sep 17 00:00:00 2001 From: Peter Eisentraut Date: Sun, 8 Oct 2017 21:44:17 -0400 Subject: Don't use SGML empty tags For DocBook XML compatibility, don't use SGML empty tags () anymore, replace by the full tag name. Add a warning option to catch future occurrences. Alexander Lakhin, Jürgen Purtz --- doc/src/sgml/gist.sgml | 402 ++++++++++++++++++++++++------------------------- 1 file changed, 201 insertions(+), 201 deletions(-) (limited to 'doc/src/sgml/gist.sgml') diff --git a/doc/src/sgml/gist.sgml b/doc/src/sgml/gist.sgml index 1648eb3672f..4e4470d439b 100644 --- a/doc/src/sgml/gist.sgml +++ b/doc/src/sgml/gist.sgml @@ -44,7 +44,7 @@ Built-in Operator Classes - The core PostgreSQL distribution + The core PostgreSQL distribution includes the GiST operator classes shown in . (Some of the optional modules described in @@ -64,142 +64,142 @@ - box_ops - box + box_ops + box - && - &> - &< - &<| - >> - << - <<| - <@ - @> - @ - |&> - |>> - ~ - ~= + && + &> + &< + &<| + >> + << + <<| + <@ + @> + @ + |&> + |>> + ~ + ~= - circle_ops - circle + circle_ops + circle - && - &> - &< - &<| - >> - << - <<| - <@ - @> - @ - |&> - |>> - ~ - ~= + && + &> + &< + &<| + >> + << + <<| + <@ + @> + @ + |&> + |>> + ~ + ~= - <-> + <-> - inet_ops - inet, cidr + inet_ops + inet, cidr - && - >> - >>= - > - >= - <> - << - <<= - < - <= - = + && + >> + >>= + > + >= + <> + << + <<= + < + <= + = - point_ops - point + point_ops + point - >> - >^ - << - <@ - <@ - <@ - <^ - ~= + >> + >^ + << + <@ + <@ + <@ + <^ + ~= - <-> + <-> - poly_ops - polygon + poly_ops + polygon - && - &> - &< - &<| - >> - << - <<| - <@ - @> - @ - |&> - |>> - ~ - ~= + && + &> + &< + &<| + >> + << + <<| + <@ + @> + @ + |&> + |>> + ~ + ~= - <-> + <-> - range_ops + range_ops any range type - && - &> - &< - >> - << - <@ - -|- - = - @> - @> + && + &> + &< + >> + << + <@ + -|- + = + @> + @> - tsquery_ops - tsquery + tsquery_ops + tsquery - <@ - @> + <@ + @> - tsvector_ops - tsvector + tsvector_ops + tsvector - @@ + @@ @@ -209,9 +209,9 @@ - For historical reasons, the inet_ops operator class is - not the default class for types inet and cidr. - To use it, mention the class name in CREATE INDEX, + For historical reasons, the inet_ops operator class is + not the default class for types inet and cidr. + To use it, mention the class name in CREATE INDEX, for example CREATE INDEX ON my_table USING GIST (my_inet_column inet_ops); @@ -270,53 +270,53 @@ CREATE INDEX ON my_table USING GIST (my_inet_column inet_ops); There are five methods that an index operator class for GiST must provide, and four that are optional. Correctness of the index is ensured - by proper implementation of the same, consistent - and union methods, while efficiency (size and speed) of the - index will depend on the penalty and picksplit + by proper implementation of the same, consistent + and union methods, while efficiency (size and speed) of the + index will depend on the penalty and picksplit methods. - Two optional methods are compress and - decompress, which allow an index to have internal tree data of + Two optional methods are compress and + decompress, which allow an index to have internal tree data of a different type than the data it indexes. The leaves are to be of the indexed data type, while the other tree nodes can be of any C struct (but - you still have to follow PostgreSQL data type rules here, - see about varlena for variable sized data). If the tree's - internal data type exists at the SQL level, the STORAGE option - of the CREATE OPERATOR CLASS command can be used. - The optional eighth method is distance, which is needed + you still have to follow PostgreSQL data type rules here, + see about varlena for variable sized data). If the tree's + internal data type exists at the SQL level, the STORAGE option + of the CREATE OPERATOR CLASS command can be used. + The optional eighth method is distance, which is needed if the operator class wishes to support ordered scans (nearest-neighbor - searches). The optional ninth method fetch is needed if the + searches). The optional ninth method fetch is needed if the operator class wishes to support index-only scans, except when the - compress method is omitted. + compress method is omitted. - consistent + consistent - Given an index entry p and a query value q, + Given an index entry p and a query value q, this function determines whether the index entry is - consistent with the query; that is, could the predicate - indexed_column - indexable_operator q be true for + consistent with the query; that is, could the predicate + indexed_column + indexable_operator q be true for any row represented by the index entry? For a leaf index entry this is equivalent to testing the indexable condition, while for an internal tree node this determines whether it is necessary to scan the subtree of the index represented by the tree node. When the result is - true, a recheck flag must also be returned. + true, a recheck flag must also be returned. This indicates whether the predicate is certainly true or only possibly - true. If recheck = false then the index has - tested the predicate condition exactly, whereas if recheck - = true the row is only a candidate match. In that case the + true. If recheck = false then the index has + tested the predicate condition exactly, whereas if recheck + = true the row is only a candidate match. In that case the system will automatically evaluate the - indexable_operator against the actual row value to see + indexable_operator against the actual row value to see if it is really a match. This convention allows GiST to support both lossless and lossy index structures. - The SQL declaration of the function must look like this: + The SQL declaration of the function must look like this: CREATE OR REPLACE FUNCTION my_consistent(internal, data_type, smallint, oid, internal) @@ -356,23 +356,23 @@ my_consistent(PG_FUNCTION_ARGS) } - Here, key is an element in the index and query - the value being looked up in the index. The StrategyNumber + Here, key is an element in the index and query + the value being looked up in the index. The StrategyNumber parameter indicates which operator of your operator class is being applied — it matches one of the operator numbers in the - CREATE OPERATOR CLASS command. + CREATE OPERATOR CLASS command. Depending on which operators you have included in the class, the data - type of query could vary with the operator, since it will + type of query could vary with the operator, since it will be whatever type is on the righthand side of the operator, which might be different from the indexed data type appearing on the lefthand side. (The above code skeleton assumes that only one type is possible; if - not, fetching the query argument value would have to depend + not, fetching the query argument value would have to depend on the operator.) It is recommended that the SQL declaration of - the consistent function use the opclass's indexed data - type for the query argument, even though the actual type + the consistent function use the opclass's indexed data + type for the query argument, even though the actual type might be something else depending on the operator. @@ -380,7 +380,7 @@ my_consistent(PG_FUNCTION_ARGS) - union + union This method consolidates information in the tree. Given a set of @@ -389,7 +389,7 @@ my_consistent(PG_FUNCTION_ARGS) - The SQL declaration of the function must look like this: + The SQL declaration of the function must look like this: CREATE OR REPLACE FUNCTION my_union(internal, internal) @@ -439,44 +439,44 @@ my_union(PG_FUNCTION_ARGS) As you can see, in this skeleton we're dealing with a data type - where union(X, Y, Z) = union(union(X, Y), Z). It's easy + where union(X, Y, Z) = union(union(X, Y), Z). It's easy enough to support data types where this is not the case, by implementing the proper union algorithm in this - GiST support method. + GiST support method. - The result of the union function must be a value of the + The result of the union function must be a value of the index's storage type, whatever that is (it might or might not be - different from the indexed column's type). The union - function should return a pointer to newly palloc()ed + different from the indexed column's type). The union + function should return a pointer to newly palloc()ed memory. You can't just return the input value as-is, even if there is no type change. - As shown above, the union function's - first internal argument is actually - a GistEntryVector pointer. The second argument is a + As shown above, the union function's + first internal argument is actually + a GistEntryVector pointer. The second argument is a pointer to an integer variable, which can be ignored. (It used to be - required that the union function store the size of its + required that the union function store the size of its result value into that variable, but this is no longer necessary.) - compress + compress Converts a data item into a format suitable for physical storage in an index page. - If the compress method is omitted, data items are stored + If the compress method is omitted, data items are stored in the index without modification. - The SQL declaration of the function must look like this: + The SQL declaration of the function must look like this: CREATE OR REPLACE FUNCTION my_compress(internal) @@ -519,7 +519,7 @@ my_compress(PG_FUNCTION_ARGS) - You have to adapt compressed_data_type to the specific + You have to adapt compressed_data_type to the specific type you're converting to in order to compress your leaf nodes, of course. @@ -527,24 +527,24 @@ my_compress(PG_FUNCTION_ARGS) - decompress + decompress Converts the stored representation of a data item into a format that can be manipulated by the other GiST methods in the operator class. - If the decompress method is omitted, it is assumed that + If the decompress method is omitted, it is assumed that the other GiST methods can work directly on the stored data format. - (decompress is not necessarily the reverse of + (decompress is not necessarily the reverse of the compress method; in particular, if compress is lossy then it's impossible - for decompress to exactly reconstruct the original - data. decompress is not necessarily equivalent - to fetch, either, since the other GiST methods might not + for decompress to exactly reconstruct the original + data. decompress is not necessarily equivalent + to fetch, either, since the other GiST methods might not require full reconstruction of the data.) - The SQL declaration of the function must look like this: + The SQL declaration of the function must look like this: CREATE OR REPLACE FUNCTION my_decompress(internal) @@ -573,7 +573,7 @@ my_decompress(PG_FUNCTION_ARGS) - penalty + penalty Returns a value indicating the cost of inserting the new @@ -584,7 +584,7 @@ my_decompress(PG_FUNCTION_ARGS) - The SQL declaration of the function must look like this: + The SQL declaration of the function must look like this: CREATE OR REPLACE FUNCTION my_penalty(internal, internal, internal) @@ -612,15 +612,15 @@ my_penalty(PG_FUNCTION_ARGS) } - For historical reasons, the penalty function doesn't - just return a float result; instead it has to store the value + For historical reasons, the penalty function doesn't + just return a float result; instead it has to store the value at the location indicated by the third argument. The return value per se is ignored, though it's conventional to pass back the address of that argument. - The penalty function is crucial to good performance of + The penalty function is crucial to good performance of the index. It'll get used at insertion time to determine which branch to follow when choosing where to add the new entry in the tree. At query time, the more balanced the index, the quicker the lookup. @@ -629,7 +629,7 @@ my_penalty(PG_FUNCTION_ARGS) - picksplit + picksplit When an index page split is necessary, this function decides which @@ -638,7 +638,7 @@ my_penalty(PG_FUNCTION_ARGS) - The SQL declaration of the function must look like this: + The SQL declaration of the function must look like this: CREATE OR REPLACE FUNCTION my_picksplit(internal, internal) @@ -725,33 +725,33 @@ my_picksplit(PG_FUNCTION_ARGS) } - Notice that the picksplit function's result is delivered - by modifying the passed-in v structure. The return + Notice that the picksplit function's result is delivered + by modifying the passed-in v structure. The return value per se is ignored, though it's conventional to pass back the - address of v. + address of v. - Like penalty, the picksplit function + Like penalty, the picksplit function is crucial to good performance of the index. Designing suitable - penalty and picksplit implementations + penalty and picksplit implementations is where the challenge of implementing well-performing - GiST indexes lies. + GiST indexes lies. - same + same Returns true if two index entries are identical, false otherwise. - (An index entry is a value of the index's storage type, + (An index entry is a value of the index's storage type, not necessarily the original indexed column's type.) - The SQL declaration of the function must look like this: + The SQL declaration of the function must look like this: CREATE OR REPLACE FUNCTION my_same(storage_type, storage_type, internal) @@ -777,7 +777,7 @@ my_same(PG_FUNCTION_ARGS) } - For historical reasons, the same function doesn't + For historical reasons, the same function doesn't just return a Boolean result; instead it has to store the flag at the location indicated by the third argument. The return value per se is ignored, though it's conventional to pass back the @@ -787,15 +787,15 @@ my_same(PG_FUNCTION_ARGS) - distance + distance - Given an index entry p and a query value q, + Given an index entry p and a query value q, this function determines the index entry's - distance from the query value. This function must be + distance from the query value. This function must be supplied if the operator class contains any ordering operators. A query using the ordering operator will be implemented by returning - index entries with the smallest distance values first, + index entries with the smallest distance values first, so the results must be consistent with the operator's semantics. For a leaf index entry the result just represents the distance to the index entry; for an internal tree node, the result must be the @@ -803,7 +803,7 @@ my_same(PG_FUNCTION_ARGS) - The SQL declaration of the function must look like this: + The SQL declaration of the function must look like this: CREATE OR REPLACE FUNCTION my_distance(internal, data_type, smallint, oid, internal) @@ -836,8 +836,8 @@ my_distance(PG_FUNCTION_ARGS) } - The arguments to the distance function are identical to - the arguments of the consistent function. + The arguments to the distance function are identical to + the arguments of the consistent function. @@ -847,31 +847,31 @@ my_distance(PG_FUNCTION_ARGS) geometric applications. For an internal tree node, the distance returned must not be greater than the distance to any of the child nodes. If the returned distance is not exact, the function must set - *recheck to true. (This is not necessary for internal tree + *recheck to true. (This is not necessary for internal tree nodes; for them, the calculation is always assumed to be inexact.) In this case the executor will calculate the accurate distance after fetching the tuple from the heap, and reorder the tuples if necessary. - If the distance function returns *recheck = true for any + If the distance function returns *recheck = true for any leaf node, the original ordering operator's return type must - be float8 or float4, and the distance function's + be float8 or float4, and the distance function's result values must be comparable to those of the original ordering operator, since the executor will sort using both distance function results and recalculated ordering-operator results. Otherwise, the - distance function's result values can be any finite float8 + distance function's result values can be any finite float8 values, so long as the relative order of the result values matches the order returned by the ordering operator. (Infinity and minus infinity are used internally to handle cases such as nulls, so it is not - recommended that distance functions return these values.) + recommended that distance functions return these values.) - fetch + fetch Converts the compressed index representation of a data item into the @@ -880,7 +880,7 @@ my_distance(PG_FUNCTION_ARGS) - The SQL declaration of the function must look like this: + The SQL declaration of the function must look like this: CREATE OR REPLACE FUNCTION my_fetch(internal) @@ -889,14 +889,14 @@ AS 'MODULE_PATHNAME' LANGUAGE C STRICT; - The argument is a pointer to a GISTENTRY struct. On - entry, its key field contains a non-NULL leaf datum in - compressed form. The return value is another GISTENTRY - struct, whose key field contains the same datum in its + The argument is a pointer to a GISTENTRY struct. On + entry, its key field contains a non-NULL leaf datum in + compressed form. The return value is another GISTENTRY + struct, whose key field contains the same datum in its original, uncompressed form. If the opclass's compress function does - nothing for leaf entries, the fetch method can return the + nothing for leaf entries, the fetch method can return the argument as-is. Or, if the opclass does not have a compress function, - the fetch method can be omitted as well, since it would + the fetch method can be omitted as well, since it would necessarily be a no-op. @@ -933,7 +933,7 @@ my_fetch(PG_FUNCTION_ARGS) If the compress method is lossy for leaf entries, the operator class cannot support index-only scans, and must not define - a fetch function. + a fetch function. @@ -942,15 +942,15 @@ my_fetch(PG_FUNCTION_ARGS) All the GiST support methods are normally called in short-lived memory - contexts; that is, CurrentMemoryContext will get reset after + contexts; that is, CurrentMemoryContext will get reset after each tuple is processed. It is therefore not very important to worry about pfree'ing everything you palloc. However, in some cases it's useful for a support method to cache data across repeated calls. To do that, allocate - the longer-lived data in fcinfo->flinfo->fn_mcxt, and - keep a pointer to it in fcinfo->flinfo->fn_extra. Such + the longer-lived data in fcinfo->flinfo->fn_mcxt, and + keep a pointer to it in fcinfo->flinfo->fn_extra. Such data will survive for the life of the index operation (e.g., a single GiST index scan, index build, or index tuple insertion). Be careful to pfree - the previous value when replacing a fn_extra value, or the leak + the previous value when replacing a fn_extra value, or the leak will accumulate for the duration of the operation. @@ -974,7 +974,7 @@ my_fetch(PG_FUNCTION_ARGS) - However, buffering index build needs to call the penalty + However, buffering index build needs to call the penalty function more often, which consumes some extra CPU resources. Also, the buffers used in the buffering build need temporary disk space, up to the size of the resulting index. Buffering can also influence the quality @@ -1002,57 +1002,57 @@ my_fetch(PG_FUNCTION_ARGS) The PostgreSQL source distribution includes several examples of index methods implemented using GiST. The core system currently provides text search - support (indexing for tsvector and tsquery) as well as + support (indexing for tsvector and tsquery) as well as R-Tree equivalent functionality for some of the built-in geometric data types - (see src/backend/access/gist/gistproc.c). The following - contrib modules also contain GiST + (see src/backend/access/gist/gistproc.c). The following + contrib modules also contain GiST operator classes: - btree_gist + btree_gist B-tree equivalent functionality for several data types - cube + cube Indexing for multidimensional cubes - hstore + hstore Module for storing (key, value) pairs - intarray + intarray RD-Tree for one-dimensional array of int4 values - ltree + ltree Indexing for tree-like structures - pg_trgm + pg_trgm Text similarity using trigram matching - seg + seg Indexing for float ranges -- cgit v1.2.3