postgres源码解析41 btree索引文件的创建--1

上述小节讲解了索引文件的物理创建，本篇讲解btree索引元组填充至索引文件的操作。先从数据结构入手，后深入执行流程。
postgres源码解析37 表创建执行全流程梳理–1
postgres源码解析37 表创建执行全流程梳理–2
postgres源码解析37 表创建执行全流程梳理–3
postgres源码解析37 表创建执行全流程梳理–4

数据结构与页面图

btree handler

该函数记录了btree 的访问方法参数和支持的回调函数

/*
 * Btree handler function: return IndexAmRoutine with access method parameters
 * and callbacks.
 */
Datum
bthandler(PG_FUNCTION_ARGS)
{
	IndexAmRoutine *amroutine = makeNode(IndexAmRoutine);

	amroutine->amstrategies = BTMaxStrategyNumber;
	amroutine->amsupport = BTNProcs;
	amroutine->amoptsprocnum = BTOPTIONS_PROC;
	amroutine->amcanorder = true;
	amroutine->amcanorderbyop = false;
	amroutine->amcanbackward = true;
	amroutine->amcanunique = true;
	amroutine->amcanmulticol = true;
	amroutine->amoptionalkey = true;
	amroutine->amsearcharray = true;
	amroutine->amsearchnulls = true;
	amroutine->amstorage = false;
	amroutine->amclusterable = true;
	amroutine->ampredlocks = true;
	amroutine->amcanparallel = true;
	amroutine->amcaninclude = true;
	amroutine->amusemaintenanceworkmem = false;
	amroutine->amparallelvacuumoptions =
		VACUUM_OPTION_PARALLEL_BULKDEL | VACUUM_OPTION_PARALLEL_COND_CLEANUP;
	amroutine->amkeytype = InvalidOid;

	amroutine->ambuild = btbuild;
	amroutine->ambuildempty = btbuildempty;
	amroutine->aminsert = btinsert;
	amroutine->ambulkdelete = btbulkdelete;
	amroutine->amvacuumcleanup = btvacuumcleanup;
	amroutine->amcanreturn = btcanreturn;
	amroutine->amcostestimate = btcostestimate;
	amroutine->amoptions = btoptions;
	amroutine->amproperty = btproperty;
	amroutine->ambuildphasename = btbuildphasename;
	amroutine->amvalidate = btvalidate;
	amroutine->amadjustmembers = btadjustmembers;
	amroutine->ambeginscan = btbeginscan;
	amroutine->amrescan = btrescan;
	amroutine->amgettuple = btgettuple;
	amroutine->amgetbitmap = btgetbitmap;
	amroutine->amendscan = btendscan;
	amroutine->ammarkpos = btmarkpos;
	amroutine->amrestrpos = btrestrpos;
	amroutine->amestimateparallelscan = btestimateparallelscan;
	amroutine->aminitparallelscan = btinitparallelscan;
	amroutine->amparallelrescan = btparallelrescan;

	PG_RETURN_POINTER(amroutine);
}
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下面简单介绍重点回调函数的功能：

索引相关的系统表

1 pg_am

postgres=# select * from pg_am;

 oid  | amname |      amhandler       | amtype 
------+--------+----------------------+--------
    2 | heap   | heap_tableam_handler | t
  403 | btree  | bthandler            | i
  405 | hash   | hashhandler          | i
  783 | gist   | gisthandler          | i
 2742 | gin    | ginhandler           | i
 4000 | spgist | spghandler           | i
 3580 | brin   | brinhandler          | i
(7 rows)

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说明：记录了每一种索引类型的访问函数句柄

2 pg_index

                                                Table "pg_catalog.pg_index"
       Column        |     Type     | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
---------------------+--------------+-----------+----------+---------+----------+-------------+--------------+-------------
 indexrelid          | oid          |           | not null |         | plain    |             |              | 
 indrelid            | oid          |           | not null |         | plain    |             |              | 
 indnatts            | smallint     |           | not null |         | plain    |             |              | 
 indnkeyatts         | smallint     |           | not null |         | plain    |             |              | 
 indisunique         | boolean      |           | not null |         | plain    |             |              | 
 indnullsnotdistinct | boolean      |           | not null |         | plain    |             |              | 
 indisprimary        | boolean      |           | not null |         | plain    |             |              | 
 indisexclusion      | boolean      |           | not null |         | plain    |             |              | 
 indimmediate        | boolean      |           | not null |         | plain    |             |              | 
 indisclustered      | boolean      |           | not null |         | plain    |             |              | 
 indisvalid          | boolean      |           | not null |         | plain    |             |              | 
 indcheckxmin        | boolean      |           | not null |         | plain    |             |              | 
 indisready          | boolean      |           | not null |         | plain    |             |              | 
 indislive           | boolean      |           | not null |         | plain    |             |              | 
 indisreplident      | boolean      |           | not null |         | plain    |             |              | 
 indkey              | int2vector   |           | not null |         | plain    |             |              | 
 indcollation        | oidvector    |           | not null |         | plain    |             |              | 
 indclass            | oidvector    |           | not null |         | plain    |             |              | 
 indoption           | int2vector   |           | not null |         | plain    |             |              | 
 indexprs            | pg_node_tree | C         |          |         | extended |             |              | 
 indpred             | pg_node_tree | C         |          |         | extended |             |              | 
Indexes:
    "pg_index_indexrelid_index" PRIMARY KEY, btree (indexrelid)
    "pg_index_indrelid_index" btree (indrelid)
Access method: heap
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3 pg_opclass

                                        Table "pg_catalog.pg_opclass"
    Column    |  Type   | Collation | Nullable | Default | Storage | Compression | Stats target | Description 
--------------+---------+-----------+----------+---------+---------+-------------+--------------+-------------
 oid          | oid     |           | not null |         | plain   |             |              | 
 opcmethod    | oid     |           | not null |         | plain   |             |              | 
 opcname      | name    |           | not null |         | plain   |             |              | 
 opcnamespace | oid     |           | not null |         | plain   |             |              | 
 opcowner     | oid     |           | not null |         | plain   |             |              | 
 opcfamily    | oid     |           | not null |         | plain   |             |              | 
 opcintype    | oid     |           | not null |         | plain   |             |              | 
 opcdefault   | boolean |           | not null |         | plain   |             |              | 
 opckeytype   | oid     |           | not null |         | plain   |             |              | 
Indexes:
    "pg_opclass_oid_index" PRIMARY KEY, btree (oid)
    "pg_opclass_am_name_nsp_index" UNIQUE CONSTRAINT, btree (opcmethod, opcname, opcnamespace)
Access method: heap

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pg_opclass定义索引访问方法的操作符类。每一个操作符类定义了一种特定数据类型和一种特定索引访问方法的索引列的语义。一个操作符类实际上指定了一个特定的操作符族可以用于一个特定可索引列数据类型。该族中可用于索引列的操作符能够接受该列的数据类型作为它们的左输入。

4 pg_opfamily

                                      Table "pg_catalog.pg_opfamily"
    Column    | Type | Collation | Nullable | Default | Storage | Compression | Stats target | Description 
--------------+------+-----------+----------+---------+---------+-------------+--------------+-------------
 oid          | oid  |           | not null |         | plain   |             |              | 
 opfmethod    | oid  |           | not null |         | plain   |             |              | 
 opfname      | name |           | not null |         | plain   |             |              | 
 opfnamespace | oid  |           | not null |         | plain   |             |              | 
 opfowner     | oid  |           | not null |         | plain   |             |              | 
Indexes:
    "pg_opfamily_oid_index" PRIMARY KEY, btree (oid)
    "pg_opfamily_am_name_nsp_index" UNIQUE CONSTRAINT, btree (opfmethod, opfname, opfnamespace)
Access method: heap
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pg_opfamily定义了操作符族。每一个操作符族是操作符和相关支持例程的集合，支持例程用于实现一个特定索引访问方法的语义。此外，按照访问方法指定的某种方式，一个族内的操作符都是“兼容的”。操作符族概念允许在索引中使用跨数据类型操作符，并可以使用访问方法语义的知识推导出。

5 pg_amop

                                           Table "pg_catalog.pg_amop"
     Column     |   Type   | Collation | Nullable | Default | Storage | Compression | Stats target | Description 
----------------+----------+-----------+----------+---------+---------+-------------+--------------+-------------
 oid            | oid      |           | not null |         | plain   |             |              | 
 amopfamily     | oid      |           | not null |         | plain   |             |              | 
 amoplefttype   | oid      |           | not null |         | plain   |             |              | 
 amoprighttype  | oid      |           | not null |         | plain   |             |              | 
 amopstrategy   | smallint |           | not null |         | plain   |             |              | 
 amoppurpose    | "char"   |           | not null |         | plain   |             |              | 
 amopopr        | oid      |           | not null |         | plain   |             |              | 
 amopmethod     | oid      |           | not null |         | plain   |             |              | 
 amopsortfamily | oid      |           | not null |         | plain   |             |              | 
Indexes:
    "pg_amop_oid_index" PRIMARY KEY, btree (oid)
    "pg_amop_fam_strat_index" UNIQUE CONSTRAINT, btree (amopfamily, amoplefttype, amoprighttype, amopstrategy)
    "pg_amop_opr_fam_index" UNIQUE CONSTRAINT, btree (amopopr, amoppurpose, amopfamily)
Access method: heap
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pg_amop存储关于与访问方法操作符族相关的操作符信息。对于一个操作符族中的每一个成员即操作符都在这个目录中有一行。一个成员可以是一个搜索操作符或者一个排序操作符。一个操作符可以出现在多个族中，但在同一个组中既不能出现在多个搜索位置也不能出现在多个排序位置（虽然不太可能出现，但是允许一个操作符同时用于搜索和排序目的）。

6 pg_amproc

                                           Table "pg_catalog.pg_amproc"
     Column      |   Type   | Collation | Nullable | Default | Storage | Compression | Stats target | Description 
-----------------+----------+-----------+----------+---------+---------+-------------+--------------+-------------
 oid             | oid      |           | not null |         | plain   |             |              | 
 amprocfamily    | oid      |           | not null |         | plain   |             |              | 
 amproclefttype  | oid      |           | not null |         | plain   |             |              | 
 amprocrighttype | oid      |           | not null |         | plain   |             |              | 
 amprocnum       | smallint |           | not null |         | plain   |             |              | 
 amproc          | regproc  |           | not null |         | plain   |             |              | 
Indexes:
    "pg_amproc_oid_index" PRIMARY KEY, btree (oid)
    "pg_amproc_fam_proc_index" UNIQUE CONSTRAINT, btree (amprocfamily, amproclefttype, amprocrighttype, amprocnum)
Access method: heap
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pg_amproc存储关于访问方法操作符族相关的支持函数。属于一个操作符族的每一个支持函数在这个目录中都有一行。