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diff --git a/doc/src/sgml/html/index-functions.html b/doc/src/sgml/html/index-functions.html new file mode 100644 index 0000000..bee58c1 --- /dev/null +++ b/doc/src/sgml/html/index-functions.html @@ -0,0 +1,483 @@ +<?xml version="1.0" encoding="UTF-8" standalone="no"?> +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>64.2. Index Access Method Functions</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="prev" href="index-api.html" title="64.1. Basic API Structure for Indexes" /><link rel="next" href="index-scanning.html" title="64.3. Index Scanning" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">64.2. Index Access Method Functions</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="index-api.html" title="64.1. Basic API Structure for Indexes">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="indexam.html" title="Chapter 64. Index Access Method Interface Definition">Up</a></td><th width="60%" align="center">Chapter 64. Index Access Method Interface Definition</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 15.4 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="index-scanning.html" title="64.3. Index Scanning">Next</a></td></tr></table><hr /></div><div class="sect1" id="INDEX-FUNCTIONS"><div class="titlepage"><div><div><h2 class="title" style="clear: both">64.2. Index Access Method Functions</h2></div></div></div><p> + The index construction and maintenance functions that an index access + method must provide in <code class="structname">IndexAmRoutine</code> are: + </p><p> +</p><pre class="programlisting"> +IndexBuildResult * +ambuild (Relation heapRelation, + Relation indexRelation, + IndexInfo *indexInfo); +</pre><p> + Build a new index. The index relation has been physically created, + but is empty. It must be filled in with whatever fixed data the + access method requires, plus entries for all tuples already existing + in the table. Ordinarily the <code class="function">ambuild</code> function will call + <code class="function">table_index_build_scan()</code> to scan the table for existing tuples + and compute the keys that need to be inserted into the index. + The function must return a palloc'd struct containing statistics about + the new index. + </p><p> +</p><pre class="programlisting"> +void +ambuildempty (Relation indexRelation); +</pre><p> + Build an empty index, and write it to the initialization fork (<code class="symbol">INIT_FORKNUM</code>) + of the given relation. This method is called only for unlogged indexes; the + empty index written to the initialization fork will be copied over the main + relation fork on each server restart. + </p><p> +</p><pre class="programlisting"> +bool +aminsert (Relation indexRelation, + Datum *values, + bool *isnull, + ItemPointer heap_tid, + Relation heapRelation, + IndexUniqueCheck checkUnique, + bool indexUnchanged, + IndexInfo *indexInfo); +</pre><p> + Insert a new tuple into an existing index. The <code class="literal">values</code> and + <code class="literal">isnull</code> arrays give the key values to be indexed, and + <code class="literal">heap_tid</code> is the TID to be indexed. + If the access method supports unique indexes (its + <code class="structfield">amcanunique</code> flag is true) then + <code class="literal">checkUnique</code> indicates the type of uniqueness check to + perform. This varies depending on whether the unique constraint is + deferrable; see <a class="xref" href="index-unique-checks.html" title="64.5. Index Uniqueness Checks">Section 64.5</a> for details. + Normally the access method only needs the <code class="literal">heapRelation</code> + parameter when performing uniqueness checking (since then it will have to + look into the heap to verify tuple liveness). + </p><p> + The <code class="literal">indexUnchanged</code> Boolean value gives a hint + about the nature of the tuple to be indexed. When it is true, + the tuple is a duplicate of some existing tuple in the index. The + new tuple is a logically unchanged successor MVCC tuple version. This + happens when an <code class="command">UPDATE</code> takes place that does not + modify any columns covered by the index, but nevertheless requires a + new version in the index. The index AM may use this hint to decide + to apply bottom-up index deletion in parts of the index where many + versions of the same logical row accumulate. Note that updating a + non-key column does not affect the value of + <code class="literal">indexUnchanged</code>. + </p><p> + The function's Boolean result value is significant only when + <code class="literal">checkUnique</code> is <code class="literal">UNIQUE_CHECK_PARTIAL</code>. + In this case a true result means the new entry is known unique, whereas + false means it might be non-unique (and a deferred uniqueness check must + be scheduled). For other cases a constant false result is recommended. + </p><p> + Some indexes might not index all tuples. If the tuple is not to be + indexed, <code class="function">aminsert</code> should just return without doing anything. + </p><p> + If the index AM wishes to cache data across successive index insertions + within an SQL statement, it can allocate space + in <code class="literal">indexInfo->ii_Context</code> and store a pointer to the + data in <code class="literal">indexInfo->ii_AmCache</code> (which will be NULL + initially). + </p><p> +</p><pre class="programlisting"> +IndexBulkDeleteResult * +ambulkdelete (IndexVacuumInfo *info, + IndexBulkDeleteResult *stats, + IndexBulkDeleteCallback callback, + void *callback_state); +</pre><p> + Delete tuple(s) from the index. This is a <span class="quote">“<span class="quote">bulk delete</span>”</span> operation + that is intended to be implemented by scanning the whole index and checking + each entry to see if it should be deleted. + The passed-in <code class="literal">callback</code> function must be called, in the style + <code class="literal">callback(<em class="replaceable"><code>TID</code></em>, callback_state) returns bool</code>, + to determine whether any particular index entry, as identified by its + referenced TID, is to be deleted. Must return either NULL or a palloc'd + struct containing statistics about the effects of the deletion operation. + It is OK to return NULL if no information needs to be passed on to + <code class="function">amvacuumcleanup</code>. + </p><p> + Because of limited <code class="varname">maintenance_work_mem</code>, + <code class="function">ambulkdelete</code> might need to be called more than once when many + tuples are to be deleted. The <code class="literal">stats</code> argument is the result + of the previous call for this index (it is NULL for the first call within a + <code class="command">VACUUM</code> operation). This allows the AM to accumulate statistics + across the whole operation. Typically, <code class="function">ambulkdelete</code> will + modify and return the same struct if the passed <code class="literal">stats</code> is not + null. + </p><p> +</p><pre class="programlisting"> +IndexBulkDeleteResult * +amvacuumcleanup (IndexVacuumInfo *info, + IndexBulkDeleteResult *stats); +</pre><p> + Clean up after a <code class="command">VACUUM</code> operation (zero or more + <code class="function">ambulkdelete</code> calls). This does not have to do anything + beyond returning index statistics, but it might perform bulk cleanup + such as reclaiming empty index pages. <code class="literal">stats</code> is whatever the + last <code class="function">ambulkdelete</code> call returned, or NULL if + <code class="function">ambulkdelete</code> was not called because no tuples needed to be + deleted. If the result is not NULL it must be a palloc'd struct. + The statistics it contains will be used to update <code class="structname">pg_class</code>, + and will be reported by <code class="command">VACUUM</code> if <code class="literal">VERBOSE</code> is given. + It is OK to return NULL if the index was not changed at all during the + <code class="command">VACUUM</code> operation, but otherwise correct stats should + be returned. + </p><p> + <code class="function">amvacuumcleanup</code> will also be called at completion of an + <code class="command">ANALYZE</code> operation. In this case <code class="literal">stats</code> is always + NULL and any return value will be ignored. This case can be distinguished + by checking <code class="literal">info->analyze_only</code>. It is recommended + that the access method do nothing except post-insert cleanup in such a + call, and that only in an autovacuum worker process. + </p><p> +</p><pre class="programlisting"> +bool +amcanreturn (Relation indexRelation, int attno); +</pre><p> + Check whether the index can support <a class="link" href="indexes-index-only-scans.html" title="11.9. Index-Only Scans and Covering Indexes"><em class="firstterm">index-only scans</em></a> on + the given column, by returning the column's original indexed value. + The attribute number is 1-based, i.e., the first column's attno is 1. + Returns true if supported, else false. + This function should always return true for included columns + (if those are supported), since there's little point in an included + column that can't be retrieved. + If the access method does not support index-only scans at all, + the <code class="structfield">amcanreturn</code> field in its <code class="structname">IndexAmRoutine</code> + struct can be set to NULL. + </p><p> +</p><pre class="programlisting"> +void +amcostestimate (PlannerInfo *root, + IndexPath *path, + double loop_count, + Cost *indexStartupCost, + Cost *indexTotalCost, + Selectivity *indexSelectivity, + double *indexCorrelation, + double *indexPages); +</pre><p> + Estimate the costs of an index scan. This function is described fully + in <a class="xref" href="index-cost-estimation.html" title="64.6. Index Cost Estimation Functions">Section 64.6</a>, below. + </p><p> +</p><pre class="programlisting"> +bytea * +amoptions (ArrayType *reloptions, + bool validate); +</pre><p> + Parse and validate the reloptions array for an index. This is called only + when a non-null reloptions array exists for the index. + <em class="parameter"><code>reloptions</code></em> is a <code class="type">text</code> array containing entries of the + form <em class="replaceable"><code>name</code></em><code class="literal">=</code><em class="replaceable"><code>value</code></em>. + The function should construct a <code class="type">bytea</code> value, which will be copied + into the <code class="structfield">rd_options</code> field of the index's relcache entry. + The data contents of the <code class="type">bytea</code> value are open for the access + method to define; most of the standard access methods use struct + <code class="structname">StdRdOptions</code>. + When <em class="parameter"><code>validate</code></em> is true, the function should report a suitable + error message if any of the options are unrecognized or have invalid + values; when <em class="parameter"><code>validate</code></em> is false, invalid entries should be + silently ignored. (<em class="parameter"><code>validate</code></em> is false when loading options + already stored in <code class="structname">pg_catalog</code>; an invalid entry could only + be found if the access method has changed its rules for options, and in + that case ignoring obsolete entries is appropriate.) + It is OK to return NULL if default behavior is wanted. + </p><p> +</p><pre class="programlisting"> +bool +amproperty (Oid index_oid, int attno, + IndexAMProperty prop, const char *propname, + bool *res, bool *isnull); +</pre><p> + The <code class="function">amproperty</code> method allows index access methods to override + the default behavior of <code class="function">pg_index_column_has_property</code> + and related functions. + If the access method does not have any special behavior for index property + inquiries, the <code class="structfield">amproperty</code> field in + its <code class="structname">IndexAmRoutine</code> struct can be set to NULL. + Otherwise, the <code class="function">amproperty</code> method will be called with + <em class="parameter"><code>index_oid</code></em> and <em class="parameter"><code>attno</code></em> both zero for + <code class="function">pg_indexam_has_property</code> calls, + or with <em class="parameter"><code>index_oid</code></em> valid and <em class="parameter"><code>attno</code></em> zero for + <code class="function">pg_index_has_property</code> calls, + or with <em class="parameter"><code>index_oid</code></em> valid and <em class="parameter"><code>attno</code></em> greater than + zero for <code class="function">pg_index_column_has_property</code> calls. + <em class="parameter"><code>prop</code></em> is an enum value identifying the property being tested, + while <em class="parameter"><code>propname</code></em> is the original property name string. + If the core code does not recognize the property name + then <em class="parameter"><code>prop</code></em> is <code class="literal">AMPROP_UNKNOWN</code>. + Access methods can define custom property names by + checking <em class="parameter"><code>propname</code></em> for a match (use <code class="function">pg_strcasecmp</code> + to match, for consistency with the core code); for names known to the core + code, it's better to inspect <em class="parameter"><code>prop</code></em>. + If the <code class="structfield">amproperty</code> method returns <code class="literal">true</code> then + it has determined the property test result: it must set <code class="literal">*res</code> + to the Boolean value to return, or set <code class="literal">*isnull</code> + to <code class="literal">true</code> to return a NULL. (Both of the referenced variables + are initialized to <code class="literal">false</code> before the call.) + If the <code class="structfield">amproperty</code> method returns <code class="literal">false</code> then + the core code will proceed with its normal logic for determining the + property test result. + </p><p> + Access methods that support ordering operators should + implement <code class="literal">AMPROP_DISTANCE_ORDERABLE</code> property testing, as the + core code does not know how to do that and will return NULL. It may + also be advantageous to implement <code class="literal">AMPROP_RETURNABLE</code> testing, + if that can be done more cheaply than by opening the index and calling + <code class="function">amcanreturn</code>, which is the core code's default behavior. + The default behavior should be satisfactory for all other standard + properties. + </p><p> +</p><pre class="programlisting"> +char * +ambuildphasename (int64 phasenum); +</pre><p> + Return the textual name of the given build phase number. + The phase numbers are those reported during an index build via the + <code class="function">pgstat_progress_update_param</code> interface. + The phase names are then exposed in the + <code class="structname">pg_stat_progress_create_index</code> view. + </p><p> +</p><pre class="programlisting"> +bool +amvalidate (Oid opclassoid); +</pre><p> + Validate the catalog entries for the specified operator class, so far as + the access method can reasonably do that. For example, this might include + testing that all required support functions are provided. + The <code class="function">amvalidate</code> function must return false if the opclass is + invalid. Problems should be reported with <code class="function">ereport</code> + messages, typically at <code class="literal">INFO</code> level. + </p><p> +</p><pre class="programlisting"> +void +amadjustmembers (Oid opfamilyoid, + Oid opclassoid, + List *operators, + List *functions); +</pre><p> + Validate proposed new operator and function members of an operator family, + so far as the access method can reasonably do that, and set their + dependency types if the default is not satisfactory. This is called + during <code class="command">CREATE OPERATOR CLASS</code> and during + <code class="command">ALTER OPERATOR FAMILY ADD</code>; in the latter + case <em class="parameter"><code>opclassoid</code></em> is <code class="literal">InvalidOid</code>. + The <code class="type">List</code> arguments are lists + of <code class="structname">OpFamilyMember</code> structs, as defined + in <code class="filename">amapi.h</code>. + + Tests done by this function will typically be a subset of those + performed by <code class="function">amvalidate</code>, + since <code class="function">amadjustmembers</code> cannot assume that it is + seeing a complete set of members. For example, it would be reasonable + to check the signature of a support function, but not to check whether + all required support functions are provided. Any problems can be + reported by throwing an error. + + The dependency-related fields of + the <code class="structname">OpFamilyMember</code> structs are initialized by + the core code to create hard dependencies on the opclass if this + is <code class="command">CREATE OPERATOR CLASS</code>, or soft dependencies on the + opfamily if this is <code class="command">ALTER OPERATOR FAMILY ADD</code>. + <code class="function">amadjustmembers</code> can adjust these fields if some other + behavior is more appropriate. For example, GIN, GiST, and SP-GiST + always set operator members to have soft dependencies on the opfamily, + since the connection between an operator and an opclass is relatively + weak in these index types; so it is reasonable to allow operator members + to be added and removed freely. Optional support functions are typically + also given soft dependencies, so that they can be removed if necessary. + </p><p> + The purpose of an index, of course, is to support scans for tuples matching + an indexable <code class="literal">WHERE</code> condition, often called a + <em class="firstterm">qualifier</em> or <em class="firstterm">scan key</em>. The semantics of + index scanning are described more fully in <a class="xref" href="index-scanning.html" title="64.3. Index Scanning">Section 64.3</a>, + below. An index access method can support <span class="quote">“<span class="quote">plain</span>”</span> index scans, + <span class="quote">“<span class="quote">bitmap</span>”</span> index scans, or both. The scan-related functions that an + index access method must or may provide are: + </p><p> +</p><pre class="programlisting"> +IndexScanDesc +ambeginscan (Relation indexRelation, + int nkeys, + int norderbys); +</pre><p> + Prepare for an index scan. The <code class="literal">nkeys</code> and <code class="literal">norderbys</code> + parameters indicate the number of quals and ordering operators that will be + used in the scan; these may be useful for space allocation purposes. + Note that the actual values of the scan keys aren't provided yet. + The result must be a palloc'd struct. + For implementation reasons the index access method + <span class="emphasis"><em>must</em></span> create this struct by calling + <code class="function">RelationGetIndexScan()</code>. In most cases + <code class="function">ambeginscan</code> does little beyond making that call and perhaps + acquiring locks; + the interesting parts of index-scan startup are in <code class="function">amrescan</code>. + </p><p> +</p><pre class="programlisting"> +void +amrescan (IndexScanDesc scan, + ScanKey keys, + int nkeys, + ScanKey orderbys, + int norderbys); +</pre><p> + Start or restart an index scan, possibly with new scan keys. (To restart + using previously-passed keys, NULL is passed for <code class="literal">keys</code> and/or + <code class="literal">orderbys</code>.) Note that it is not allowed for + the number of keys or order-by operators to be larger than + what was passed to <code class="function">ambeginscan</code>. In practice the restart + feature is used when a new outer tuple is selected by a nested-loop join + and so a new key comparison value is needed, but the scan key structure + remains the same. + </p><p> +</p><pre class="programlisting"> +bool +amgettuple (IndexScanDesc scan, + ScanDirection direction); +</pre><p> + Fetch the next tuple in the given scan, moving in the given + direction (forward or backward in the index). Returns true if a tuple was + obtained, false if no matching tuples remain. In the true case the tuple + TID is stored into the <code class="literal">scan</code> structure. Note that + <span class="quote">“<span class="quote">success</span>”</span> means only that the index contains an entry that matches + the scan keys, not that the tuple necessarily still exists in the heap or + will pass the caller's snapshot test. On success, <code class="function">amgettuple</code> + must also set <code class="literal">scan->xs_recheck</code> to true or false. + False means it is certain that the index entry matches the scan keys. + True means this is not certain, and the conditions represented by the + scan keys must be rechecked against the heap tuple after fetching it. + This provision supports <span class="quote">“<span class="quote">lossy</span>”</span> index operators. + Note that rechecking will extend only to the scan conditions; a partial + index predicate (if any) is never rechecked by <code class="function">amgettuple</code> + callers. + </p><p> + If the index supports <a class="link" href="indexes-index-only-scans.html" title="11.9. Index-Only Scans and Covering Indexes">index-only + scans</a> (i.e., <code class="function">amcanreturn</code> returns true for any + of its columns), + then on success the AM must also check <code class="literal">scan->xs_want_itup</code>, + and if that is true it must return the originally indexed data for the + index entry. Columns for which <code class="function">amcanreturn</code> returns + false can be returned as nulls. + The data can be returned in the form of an + <code class="structname">IndexTuple</code> pointer stored at <code class="literal">scan->xs_itup</code>, + with tuple descriptor <code class="literal">scan->xs_itupdesc</code>; or in the form of + a <code class="structname">HeapTuple</code> pointer stored at <code class="literal">scan->xs_hitup</code>, + with tuple descriptor <code class="literal">scan->xs_hitupdesc</code>. (The latter + format should be used when reconstructing data that might possibly not fit + into an <code class="structname">IndexTuple</code>.) In either case, + management of the data referenced by the pointer is the access method's + responsibility. The data must remain good at least until the next + <code class="function">amgettuple</code>, <code class="function">amrescan</code>, or <code class="function">amendscan</code> + call for the scan. + </p><p> + The <code class="function">amgettuple</code> function need only be provided if the access + method supports <span class="quote">“<span class="quote">plain</span>”</span> index scans. If it doesn't, the + <code class="structfield">amgettuple</code> field in its <code class="structname">IndexAmRoutine</code> + struct must be set to NULL. + </p><p> +</p><pre class="programlisting"> +int64 +amgetbitmap (IndexScanDesc scan, + TIDBitmap *tbm); +</pre><p> + Fetch all tuples in the given scan and add them to the caller-supplied + <code class="type">TIDBitmap</code> (that is, OR the set of tuple IDs into whatever set is already + in the bitmap). The number of tuples fetched is returned (this might be + just an approximate count, for instance some AMs do not detect duplicates). + While inserting tuple IDs into the bitmap, <code class="function">amgetbitmap</code> can + indicate that rechecking of the scan conditions is required for specific + tuple IDs. This is analogous to the <code class="literal">xs_recheck</code> output parameter + of <code class="function">amgettuple</code>. Note: in the current implementation, support + for this feature is conflated with support for lossy storage of the bitmap + itself, and therefore callers recheck both the scan conditions and the + partial index predicate (if any) for recheckable tuples. That might not + always be true, however. + <code class="function">amgetbitmap</code> and + <code class="function">amgettuple</code> cannot be used in the same index scan; there + are other restrictions too when using <code class="function">amgetbitmap</code>, as explained + in <a class="xref" href="index-scanning.html" title="64.3. Index Scanning">Section 64.3</a>. + </p><p> + The <code class="function">amgetbitmap</code> function need only be provided if the access + method supports <span class="quote">“<span class="quote">bitmap</span>”</span> index scans. If it doesn't, the + <code class="structfield">amgetbitmap</code> field in its <code class="structname">IndexAmRoutine</code> + struct must be set to NULL. + </p><p> +</p><pre class="programlisting"> +void +amendscan (IndexScanDesc scan); +</pre><p> + End a scan and release resources. The <code class="literal">scan</code> struct itself + should not be freed, but any locks or pins taken internally by the + access method must be released, as well as any other memory allocated + by <code class="function">ambeginscan</code> and other scan-related functions. + </p><p> +</p><pre class="programlisting"> +void +ammarkpos (IndexScanDesc scan); +</pre><p> + Mark current scan position. The access method need only support one + remembered scan position per scan. + </p><p> + The <code class="function">ammarkpos</code> function need only be provided if the access + method supports ordered scans. If it doesn't, + the <code class="structfield">ammarkpos</code> field in its <code class="structname">IndexAmRoutine</code> + struct may be set to NULL. + </p><p> +</p><pre class="programlisting"> +void +amrestrpos (IndexScanDesc scan); +</pre><p> + Restore the scan to the most recently marked position. + </p><p> + The <code class="function">amrestrpos</code> function need only be provided if the access + method supports ordered scans. If it doesn't, + the <code class="structfield">amrestrpos</code> field in its <code class="structname">IndexAmRoutine</code> + struct may be set to NULL. + </p><p> + In addition to supporting ordinary index scans, some types of index + may wish to support <em class="firstterm">parallel index scans</em>, which allow + multiple backends to cooperate in performing an index scan. The + index access method should arrange things so that each cooperating + process returns a subset of the tuples that would be performed by + an ordinary, non-parallel index scan, but in such a way that the + union of those subsets is equal to the set of tuples that would be + returned by an ordinary, non-parallel index scan. Furthermore, while + there need not be any global ordering of tuples returned by a parallel + scan, the ordering of that subset of tuples returned within each + cooperating backend must match the requested ordering. The following + functions may be implemented to support parallel index scans: + </p><p> +</p><pre class="programlisting"> +Size +amestimateparallelscan (void); +</pre><p> + Estimate and return the number of bytes of dynamic shared memory which + the access method will be needed to perform a parallel scan. (This number + is in addition to, not in lieu of, the amount of space needed for + AM-independent data in <code class="structname">ParallelIndexScanDescData</code>.) + </p><p> + It is not necessary to implement this function for access methods which + do not support parallel scans or for which the number of additional bytes + of storage required is zero. + </p><p> +</p><pre class="programlisting"> +void +aminitparallelscan (void *target); +</pre><p> + This function will be called to initialize dynamic shared memory at the + beginning of a parallel scan. <em class="parameter"><code>target</code></em> will point to at least + the number of bytes previously returned by + <code class="function">amestimateparallelscan</code>, and this function may use that + amount of space to store whatever data it wishes. + </p><p> + It is not necessary to implement this function for access methods which + do not support parallel scans or in cases where the shared memory space + required needs no initialization. + </p><p> +</p><pre class="programlisting"> +void +amparallelrescan (IndexScanDesc scan); +</pre><p> + This function, if implemented, will be called when a parallel index scan + must be restarted. It should reset any shared state set up by + <code class="function">aminitparallelscan</code> such that the scan will be restarted from + the beginning. + </p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="index-api.html" title="64.1. Basic API Structure for Indexes">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="indexam.html" title="Chapter 64. Index Access Method Interface Definition">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="index-scanning.html" title="64.3. Index Scanning">Next</a></td></tr><tr><td width="40%" align="left" valign="top">64.1. Basic API Structure for Indexes </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 15.4 Documentation">Home</a></td><td width="40%" align="right" valign="top"> 64.3. Index Scanning</td></tr></table></div></body></html>
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