本篇内容主要讲解“怎么理解PostgreSQL的分区表”，感兴趣的朋友不妨来看看。本文介绍的方法操作简单快捷，实用性强。下面就让小编来带大家学习“怎么理解PostgreSQL的分区表”吧!
在PG中,分区表通过"继承"的方式实现,这里就会存在一个问题,就是在插入数据时,PG如何确定数据应该插入到哪个目标分区?在PG中,通过函数ExecPrepareTupleRouting为路由待插入的元组做准备,主要的目的是确定元组所在的分区。
一、数据结构
ModifyTable
ModifyTable Node
通过插入、更新或删除，将子计划生成的行应用到结果表。
/* ----------------
* ModifyTable node -
* Apply rows produced by subplan(s) to result table(s),
* by inserting, updating, or deleting.
* 通过插入、更新或删除，将子计划生成的行应用到结果表。
*
* If the originally named target table is a partitioned table, both
* nominalRelation and rootRelation contain the RT index of the partition
* root, which is not otherwise mentioned in the plan. Otherwise rootRelation
* is zero. However, nominalRelation will always be set, as it's the rel that
* EXPLAIN should claim is the INSERT/UPDATE/DELETE target.
* 如果最初命名的目标表是分区表，则nominalRelation和rootRelation都包含分区根的RT索引，计划中没有另外提到这个索引。
* 否则，根关系为零。但是，总是会设置名义关系，nominalRelation因为EXPLAIN应该声明的rel是INSERT/UPDATE/DELETE目标关系。
*
* Note that rowMarks and epqParam are presumed to be valid for all the
* subplan(s); they can't contain any info that varies across subplans.
* 注意，rowMarks和epqParam被假定对所有子计划有效;
* 它们不能包含任何在子计划中变化的信息。
* ----------------
*/
typedef struct ModifyTable
{
Plan plan;
CmdType operation; /* 操作类型;INSERT, UPDATE, or DELETE */
bool canSetTag; /* 是否需要设置tag?do we set the command tag/es_processed? */
Index nominalRelation; /* 用于EXPLAIN的父RT索引;Parent RT index for use of EXPLAIN */
Index rootRelation; /* 根Root RT索引(如目标为分区表);Root RT index, if target is partitioned */
bool partColsUpdated; /* 更新了层次结构中的分区关键字;some part key in hierarchy updated */
List *resultRelations; /* RT索引的整型链表;integer list of RT indexes */
int resultRelIndex; /* 计划链表中第一个resultRel的索引;index of first resultRel in plan's list */
int rootResultRelIndex; /* 分区表根索引;index of the partitioned table root */
List *plans; /* 生成源数据的计划链表;plan(s) producing source data */
List *withCheckOptionLists; /* 每一个目标表均具备的WCO链表;per-target-table WCO lists */
List *returningLists; /* 每一个目标表均具备的RETURNING链表;per-target-table RETURNING tlists */
List *fdwPrivLists; /* 每一个目标表的FDW私有数据链表;per-target-table FDW private data lists */
Bitmapset *fdwDirectModifyPlans; /* FDW DM计划索引位图;indices of FDW DM plans */
List *rowMarks; /* rowMarks链表;PlanRowMarks (non-locking only) */
int epqParam; /* EvalPlanQual再解析使用的参数ID;ID of Param for EvalPlanQual re-eval */
OnConflictAction onConflictAction; /* ON CONFLICT action */
List *arbiterIndexes; /* 冲突仲裁器索引表;List of ON CONFLICT arbiter index OIDs */
List *onConflictSet; /* SET for INSERT ON CONFLICT DO UPDATE */
Node *onConflictWhere; /* WHERE for ON CONFLICT UPDATE */
Index exclRelRTI; /* RTI of the EXCLUDED pseudo relation */
List *exclRelTlist; /* 已排除伪关系的投影列链表;tlist of the EXCLUDED pseudo relation */
} ModifyTable;
ResultRelInfo
ResultRelInfo结构体
每当更新一个现有的关系时，我们必须更新关系上的索引，也许还需要触发触发器。ResultRelInfo保存关于结果关系所需的所有信息，包括索引。
/*
* ResultRelInfo
* ResultRelInfo结构体
*
* Whenever we update an existing relation, we have to update indexes on the
* relation, and perhaps also fire triggers. ResultRelInfo holds all the
* information needed about a result relation, including indexes.
* 每当更新一个现有的关系时，我们必须更新关系上的索引，也许还需要触发触发器。
* ResultRelInfo保存关于结果关系所需的所有信息，包括索引。
*
* Normally, a ResultRelInfo refers to a table that is in the query's
* range table; then ri_RangeTableIndex is the RT index and ri_RelationDesc
* is just a copy of the relevant es_relations[] entry. But sometimes,
* in ResultRelInfos used only for triggers, ri_RangeTableIndex is zero
* and ri_RelationDesc is a separately-opened relcache pointer that needs
* to be separately closed. See ExecGetTriggerResultRel.
* 通常，ResultRelInfo是指查询范围表中的表;
* ri_RangeTableIndex是RT索引，而ri_RelationDesc只是相关es_relations[]条目的副本。
* 但有时，在只用于触发器的ResultRelInfos中，ri_RangeTableIndex为零(NULL)，
* 而ri_RelationDesc是一个需要单独关闭单独打开的relcache指针。
* 具体可参考ExecGetTriggerResultRel结构体。
*/
typedef struct ResultRelInfo
{
NodeTag type;
/* result relation's range table index, or 0 if not in range table */
//RTE索引
Index ri_RangeTableIndex;
/* relation descriptor for result relation */
//结果/目标relation的描述符
Relation ri_RelationDesc;
/* # of indices existing on result relation */
//目标关系中索引数目
int ri_NumIndices;
/* array of relation descriptors for indices */
//索引的关系描述符数组(索引视为一个relation)
RelationPtr ri_IndexRelationDescs;
/* array of key/attr info for indices */
//索引的键/属性数组
IndexInfo **ri_IndexRelationInfo;
/* triggers to be fired, if any */
//触发的索引
TriggerDesc *ri_TrigDesc;
/* cached lookup info for trigger functions */
//触发器函数(缓存)
FmgrInfo *ri_TrigFunctions;
/* array of trigger WHEN expr states */
//WHEN表达式状态的触发器数组
ExprState **ri_TrigWhenExprs;
/* optional runtime measurements for triggers */
//可选的触发器运行期度量器
Instrumentation *ri_TrigInstrument;
/* FDW callback functions, if foreign table */
//FDW回调函数
struct FdwRoutine *ri_FdwRoutine;
/* available to save private state of FDW */
//可用于存储FDW的私有状态
void *ri_FdwState;
/* true when modifying foreign table directly */
//直接更新FDW时为T
bool ri_usesFdwDirectModify;
/* list of WithCheckOption's to be checked */
//WithCheckOption链表
List *ri_WithCheckOptions;
/* list of WithCheckOption expr states */
//WithCheckOption表达式链表
List *ri_WithCheckOptionExprs;
/* array of constraint-checking expr states */
//约束检查表达式状态数组
ExprState **ri_ConstraintExprs;
/* for removing junk attributes from tuples */
//用于从元组中删除junk属性
JunkFilter *ri_junkFilter;
/* list of RETURNING expressions */
//RETURNING表达式链表
List *ri_returningList;
/* for computing a RETURNING list */
//用于计算RETURNING链表
ProjectionInfo *ri_projectReturning;
/* list of arbiter indexes to use to check conflicts */
//用于检查冲突的仲裁器索引的列表
List *ri_onConflictArbiterIndexes;
/* ON CONFLICT evaluation state */
//ON CONFLICT解析状态
OnConflictSetState *ri_onConflict;
/* partition check expression */
//分区检查表达式链表
List *ri_PartitionCheck;
/* partition check expression state */
//分区检查表达式状态
ExprState *ri_PartitionCheckExpr;
/* relation descriptor for root partitioned table */
//分区root根表描述符
Relation ri_PartitionRoot;
/* Additional information specific to partition tuple routing */
//额外的分区元组路由信息
struct PartitionRoutingInfo *ri_PartitionInfo;
} ResultRelInfo;
PartitionRoutingInfo
PartitionRoutingInfo结构体
分区路由信息,用于将元组路由到表分区的结果关系信息。
/*
* PartitionRoutingInfo
* PartitionRoutingInfo - 分区路由信息
*
* Additional result relation information specific to routing tuples to a
* table partition.
* 用于将元组路由到表分区的结果关系信息。
*/
typedef struct PartitionRoutingInfo
{
/*
* Map for converting tuples in root partitioned table format into
* partition format, or NULL if no conversion is required.
* 映射，用于将根分区表格式的元组转换为分区格式，如果不需要转换，则转换为NULL。
*/
TupleConversionMap *pi_RootToPartitionMap;
/*
* Map for converting tuples in partition format into the root partitioned
* table format, or NULL if no conversion is required.
* 映射，用于将分区格式的元组转换为根分区表格式，如果不需要转换，则转换为NULL。
*/
TupleConversionMap *pi_PartitionToRootMap;
/*
* Slot to store tuples in partition format, or NULL when no translation
* is required between root and partition.
* 以分区格式存储元组的slot.在根分区和分区之间不需要转换时为NULL。
*/
TupleTableSlot *pi_PartitionTupleSlot;
} PartitionRoutingInfo;
TupleConversionMap
TupleConversionMap结构体,用于存储元组转换映射信息.
typedef struct TupleConversionMap
{
TupleDesc indesc; /* 源行类型的描述符;tupdesc for source rowtype */
TupleDesc outdesc; /* 结果行类型的描述符;tupdesc for result rowtype */
AttrNumber *attrMap; /* 输入字段的索引信息,0表示NULL;indexes of input fields, or 0 for null */
Datum *invalues; /* 析构源数据的工作空间;workspace for deconstructing source */
bool *inisnull; //是否为NULL标记数组
Datum *outvalues; /* 构造结果的工作空间;workspace for constructing result */
bool *outisnull; //null标记
} TupleConversionMap;
二、源码解读
ExecPrepareTupleRouting函数确定要插入slot中的tuple所属的分区，同时修改mtstate和estate等相关信息,为后续实际的插入作准备。
/*
* ExecPrepareTupleRouting --- prepare for routing one tuple
* ExecPrepareTupleRouting --- 为路由一个元组做准备
*
* Determine the partition in which the tuple in slot is to be inserted,
* and modify mtstate and estate to prepare for it.
* 确定要插入slot中tuple的分区，并修改mtstate和estate以为插入作准备。
*
* Caller must revert the estate changes after executing the insertion!
* In mtstate, transition capture changes may also need to be reverted.
* 调用方必须在执行插入之后恢复estate中被修改的属性值!
* 在mtstate中，转换捕获更改也可能需要恢复。
*
* Returns a slot holding the tuple of the partition rowtype.
* 返回包含分区rowtype元组的槽位。
*/
static TupleTableSlot *
ExecPrepareTupleRouting(ModifyTableState *mtstate,
EState *estate,
PartitionTupleRouting *proute,
ResultRelInfo *targetRelInfo,
TupleTableSlot *slot)
{
ModifyTable *node;//ModifyTable节点
int partidx;//分区索引
ResultRelInfo *partrel;//ResultRelInfo结构体指针(数组)
HeapTuple tuple;//元组
/*
* Determine the target partition. If ExecFindPartition does not find a
* partition after all, it doesn't return here; otherwise, the returned
* value is to be used as an index into the arrays for the ResultRelInfo
* and TupleConversionMap for the partition.
* 确定目标分区。
* 如果ExecFindPartition最终没有找到分区，它不会在这里返回;
* 否则，返回值将用作分区的ResultRelInfo和TupleConversionMap数组的索引。
*/
partidx = ExecFindPartition(targetRelInfo,
proute->partition_dispatch_info,
slot,
estate);
Assert(partidx >= 0 && partidx < proute->num_partitions);
/*
* Get the ResultRelInfo corresponding to the selected partition; if not
* yet there, initialize it.
* 获取与所选分区对应的ResultRelInfo;如果还没有，则初始化。
*/
partrel = proute->partitions[partidx];
if (partrel == NULL)
partrel = ExecInitPartitionInfo(mtstate, targetRelInfo,
proute, estate,
partidx);
/*
* Check whether the partition is routable if we didn't yet
* 检查分区是否可路由
*
* Note: an UPDATE of a partition key invokes an INSERT that moves the
* tuple to a new partition. This check would be applied to a subplan
* partition of such an UPDATE that is chosen as the partition to route
* the tuple to. The reason we do this check here rather than in
* ExecSetupPartitionTupleRouting is to avoid aborting such an UPDATE
* unnecessarily due to non-routable subplan partitions that may not be
* chosen for update tuple movement after all.
* 注意:分区键的更新调用将元组移动到新分区的插入。
* 此检查将应用于此类更新的子计划分区，该分区被选择为将元组路由到的分区。
* 在这里而不是在ExecSetupPartitionTupleRouting中执行此检查的原因是
为了避免由于无法路由的子计划分区而不必要地中止这样的更新，这些分区可能最终不会被选择用于更新元组移动。
*/
if (!partrel->ri_PartitionReadyForRouting)
{
/* Verify the partition is a valid target for INSERT. */
//验证分区是否可用于INSERT
CheckValidResultRel(partrel, CMD_INSERT);
/* Set up information needed for routing tuples to the partition. */
//设置将元组路由到分区所需的信息。
ExecInitRoutingInfo(mtstate, estate, proute, partrel, partidx);
}
/*
* Make it look like we are inserting into the partition.
* 让它看起来像是插入到分区中。
*/
estate->es_result_relation_info = partrel;
/* Get the heap tuple out of the given slot. */
//从给定的slot中获取heap tuple
tuple = ExecMaterializeSlot(slot);
/*
* If we're capturing transition tuples, we might need to convert from the
* partition rowtype to parent rowtype.
* 如果正在捕获转换元组，可能需要将分区行类型转换为根分区表的行类型。
*/
if (mtstate->mt_transition_capture != NULL)
{
if (partrel->ri_TrigDesc &&
partrel->ri_TrigDesc->trig_insert_before_row)
{
/*
* If there are any BEFORE triggers on the partition, we'll have
* to be ready to convert their result back to tuplestore format.
* 如果分区上有BEFORE触发器，必须准备将它们的结果转换回tuplestore格式。
*/
mtstate->mt_transition_capture->tcs_original_insert_tuple = NULL;
mtstate->mt_transition_capture->tcs_map =
TupConvMapForLeaf(proute, targetRelInfo, partidx);
}
else
{
/*
* Otherwise, just remember the original unconverted tuple, to
* avoid a needless round trip conversion.
* 否则，只需记住原始的未转换元组，以避免不必要的来回转换。
*/
mtstate->mt_transition_capture->tcs_original_insert_tuple = tuple;
mtstate->mt_transition_capture->tcs_map = NULL;
}
}
if (mtstate->mt_oc_transition_capture != NULL)
{
mtstate->mt_oc_transition_capture->tcs_map =
TupConvMapForLeaf(proute, targetRelInfo, partidx);
}
/*
* Convert the tuple, if necessary.
* 如需要,转换元组
*/
ConvertPartitionTupleSlot(proute->parent_child_tupconv_maps[partidx],
tuple,
proute->partition_tuple_slot,
&slot);
/* Initialize information needed to handle ON CONFLICT DO UPDATE. */
//如为ON CONFLICT DO UPDATE模式,则初始化相关信息
Assert(mtstate != NULL);
node = (ModifyTable *) mtstate->ps.plan;
if (node->onConflictAction == ONCONFLICT_UPDATE)
{
Assert(mtstate->mt_existing != NULL);
ExecSetSlotDescriptor(mtstate->mt_existing,
RelationGetDescr(partrel->ri_RelationDesc));
Assert(mtstate->mt_conflproj != NULL);
ExecSetSlotDescriptor(mtstate->mt_conflproj,
partrel->ri_onConflict->oc_ProjTupdesc);
}
return slot;
}
/*
* ExecFetchSlotHeapTuple - fetch HeapTuple representing the slot's content
* ExecFetchSlotHeapTuple - 根据slot提取HeapTuple
*
* The returned HeapTuple represents the slot's content as closely as
* possible.
* 返回的HeapTuple尽可能就是slot的内容。
*
* If materialize is true, the contents of the slots will be made independent
* from the underlying storage (i.e. all buffer pins are release, memory is
* allocated in the slot's context).
* 如果materialize为T，slot的内容将独立于底层存储(即释放所有缓冲区pin，在slot的上下文中分配内存)。
*
* If shouldFree is not-NULL it'll be set to true if the returned tuple has
* been allocated in the calling memory context, and must be freed by the
* caller (via explicit pfree() or a memory context reset).
* 如果shouldFree not-NULL，那么如果返回的元组已经在调用内存上下文中分配，
* 并且必须由调用方释放(通过显式pfree()或内存上下文重置)。
*
* NB: If materialize is true, modifications of the returned tuple are
* allowed. But it depends on the type of the slot whether such modifications
* will also affect the slot's contents. While that is not the nicest
* behaviour, all such modifcations are in the process of being removed.
* 注意:如果materialize为T，则允许修改返回的元组。
* 但这取决于slot的类型，这种修改是否也会影响slot的内容。
* 虽然这不是最好的行为，但所有这些修改都在被移除的过程中。
*/
HeapTuple
ExecFetchSlotHeapTuple(TupleTableSlot *slot, bool materialize, bool *shouldFree)
{
/*
* sanity checks
* 安全检查
*/
Assert(slot != NULL);
Assert(!TTS_EMPTY(slot));
/* Materialize the tuple so that the slot "owns" it, if requested. */
//物化元组，以便slot“拥有”它(如要求)。
if (materialize)
slot->tts_ops->materialize(slot);
if (slot->tts_ops->get_heap_tuple == NULL)
{
if (shouldFree)
*shouldFree = true;
return slot->tts_ops->copy_heap_tuple(slot);//返回slot拷贝
}
else
{
if (shouldFree)
*shouldFree = false;
return slot->tts_ops->get_heap_tuple(slot);//直接返回slot
}
}
三、跟踪分析
测试脚本如下
-- Hash Partition drop table if exists t_hash_partition; create table t_hash_partition (c1 int not null,c2 varchar(40),c3 varchar(40)) partition by hash(c1); create table t_hash_partition_1 partition of t_hash_partition for values with (modulus 6,remainder 0); create table t_hash_partition_2 partition of t_hash_partition for values with (modulus 6,remainder 1); create table t_hash_partition_3 partition of t_hash_partition for values with (modulus 6,remainder 2); create table t_hash_partition_4 partition of t_hash_partition for values with (modulus 6,remainder 3); create table t_hash_partition_5 partition of t_hash_partition for values with (modulus 6,remainder 4); create table t_hash_partition_6 partition of t_hash_partition for values with (modulus 6,remainder 5); -- delete from t_hash_partition where c1 = 0; insert into t_hash_partition(c1,c2,c3) VALUES(0,'HASH0','HAHS0');
启动gdb,设置断点,进入ExecPrepareTupleRouting
(gdb) b ExecPrepareTupleRouting Breakpoint 1 at 0x710b1e: file nodeModifyTable.c, line 1712. (gdb) c Continuing. Breakpoint 1, ExecPrepareTupleRouting (mtstate=0x1e4de60, estate=0x1e4daf8, proute=0x1e4eb48, targetRelInfo=0x1e4dd48, slot=0x1e4e4e0) at nodeModifyTable.c:1712 1712 partidx = ExecFindPartition(targetRelInfo,
查看函数调用栈
ExecPrepareTupleRouting在ExecModifyTable Node中被调用,为后续的插入作准备.
(gdb) bt #0 ExecPrepareTupleRouting (mtstate=0x1e4de60, estate=0x1e4daf8, proute=0x1e4eb48, targetRelInfo=0x1e4dd48, slot=0x1e4e4e0) at nodeModifyTable.c:1712 #1 0x0000000000711602 in ExecModifyTable (pstate=0x1e4de60) at nodeModifyTable.c:2157 #2 0x00000000006e4c30 in ExecProcNodeFirst (node=0x1e4de60) at execProcnode.c:445 #3 0x00000000006d9974 in ExecProcNode (node=0x1e4de60) at ../../../src/include/executor/executor.h:237 #4 0x00000000006dc22d in ExecutePlan (estate=0x1e4daf8, planstate=0x1e4de60, use_parallel_mode=false, operation=CMD_INSERT, sendTuples=false, numberTuples=0, direction=ForwardScanDirection, dest=0x1e67e90, execute_once=true) at execMain.c:1723 #5 0x00000000006d9f5c in standard_ExecutorRun (queryDesc=0x1e39d68, direction=ForwardScanDirection, count=0, execute_once=true) at execMain.c:364 #6 0x00000000006d9d7f in ExecutorRun (queryDesc=0x1e39d68, direction=ForwardScanDirection, count=0, execute_once=true) at execMain.c:307 #7 0x00000000008cbdb3 in ProcessQuery (plan=0x1e67d18, sourceText=0x1d60ec8 "insert into t_hash_partition(c1,c2,c3) VALUES(0,'HASH0','HAHS0');", params=0x0, queryEnv=0x0, dest=0x1e67e90, completionTag=0x7ffdcf148b20 "") at pquery.c:161 #8 0x00000000008cd6f9 in PortalRunMulti (portal=0x1dc6538, isTopLevel=true, setHoldSnapshot=false, dest=0x1e67e90, altdest=0x1e67e90, completionTag=0x7ffdcf148b20 "") at pquery.c:1286 #9 0x00000000008cccb9 in PortalRun (portal=0x1dc6538, count=9223372036854775807, isTopLevel=true, run_once=true, dest=0x1e67e90, altdest=0x1e67e90, completionTag=0x7ffdcf148b20 "") at pquery.c:799 #10 0x00000000008c6b1e in exec_simple_query ( query_string=0x1d60ec8 "insert into t_hash_partition(c1,c2,c3) VALUES(0,'HASH0','HAHS0');") at postgres.c:1145 #11 0x00000000008cae70 in PostgresMain (argc=1, argv=0x1d8aba8, dbname=0x1d8aa10 "testdb", username=0x1d5dba8 "xdb") at postgres.c:4182
找到该元组所在的分区
(gdb) n 1716 Assert(partidx >= 0 && partidx < proute->num_partitions); (gdb) p partidx $1 = 2
获取与所选分区对应的ResultRelInfo;如果还没有，则初始化
(gdb) n 1722 partrel = proute->partitions[partidx]; (gdb) 1723 if (partrel == NULL) (gdb) p *partrel Cannot access memory at address 0x0 (gdb) n 1724 partrel = ExecInitPartitionInfo(mtstate, targetRelInfo,
初始化后的partrel
(gdb) p *partrel
$2 = {type = T_ResultRelInfo, ri_RangeTableIndex = 1, ri_RelationDesc = 0x1e7c940, ri_NumIndices = 0,
ri_IndexRelationDescs = 0x0, ri_IndexRelationInfo = 0x0, ri_TrigDesc = 0x0, ri_TrigFunctions = 0x0,
ri_TrigWhenExprs = 0x0, ri_TrigInstrument = 0x0, ri_FdwRoutine = 0x0, ri_FdwState = 0x0, ri_usesFdwDirectModify = false,
ri_WithCheckOptions = 0x0, ri_WithCheckOptionExprs = 0x0, ri_ConstraintExprs = 0x0, ri_junkFilter = 0x0,
ri_returningList = 0x0, ri_projectReturning = 0x0, ri_onConflictArbiterIndexes = 0x0, ri_onConflict = 0x0,
ri_PartitionCheck = 0x1e4f538, ri_PartitionCheckExpr = 0x0, ri_PartitionRoot = 0x1e7c2f8,
ri_PartitionReadyForRouting = true}
目标分区描述符–>t_hash_partition_3
(gdb) p *partrel->ri_RelationDesc
$3 = {rd_node = {spcNode = 1663, dbNode = 16402, relNode = 16995}, rd_smgr = 0x1e34510, rd_refcnt = 1, rd_backend = -1,
rd_islocaltemp = false, rd_isnailed = false, rd_isvalid = true, rd_indexvalid = 0 '/000', rd_statvalid = false,
rd_createSubid = 0, rd_newRelfilenodeSubid = 0, rd_rel = 0x1e7c1e0, rd_att = 0x1e7cb58, rd_id = 16995, rd_lockInfo = {
lockRelId = {relId = 16995, dbId = 16402}}, rd_rules = 0x0, rd_rulescxt = 0x0, trigdesc = 0x0, rd_rsdesc = 0x0,
rd_fkeylist = 0x0, rd_fkeyvalid = false, rd_partkeycxt = 0x0, rd_partkey = 0x0, rd_pdcxt = 0x0, rd_partdesc = 0x0,
rd_partcheck = 0x1e7aa30, rd_indexlist = 0x0, rd_oidindex = 0, rd_pkindex = 0, rd_replidindex = 0, rd_statlist = 0x0,
rd_indexattr = 0x0, rd_projindexattr = 0x0, rd_keyattr = 0x0, rd_pkattr = 0x0, rd_idattr = 0x0, rd_projidx = 0x0,
rd_pubactions = 0x0, rd_options = 0x0, rd_index = 0x0, rd_indextuple = 0x0, rd_amhandler = 0, rd_indexcxt = 0x0,
rd_amroutine = 0x0, rd_opfamily = 0x0, rd_opcintype = 0x0, rd_support = 0x0, rd_supportinfo = 0x0, rd_indoption = 0x0,
rd_indexprs = 0x0, rd_indpred = 0x0, rd_exclops = 0x0, rd_exclprocs = 0x0, rd_exclstrats = 0x0, rd_amcache = 0x0,
rd_indcollation = 0x0, rd_fdwroutine = 0x0, rd_toastoid = 0, pgstat_info = 0x1de40b0}
------------------
testdb=# select oid,relname from pg_class where oid=16995;
oid | relname
-------+--------------------
16995 | t_hash_partition_3
(1 row)
-----------------
该分区是可路由的
(gdb) p partrel->ri_PartitionReadyForRouting $4 = true
设置estate变量(让它看起来像是插入到分区中)/物化tuple
(gdb) n
1751 estate->es_result_relation_info = partrel;
(gdb)
1754 tuple = ExecMaterializeSlot(slot);
(gdb)
1760 if (mtstate->mt_transition_capture != NULL)
(gdb) p tuple
$5 = (HeapTuple) 0x1e4f4e0
(gdb) p *tuple
$6 = {t_len = 40, t_self = {ip_blkid = {bi_hi = 65535, bi_lo = 65535}, ip_posid = 0}, t_tableOid = 0, t_data = 0x1e4f4f8}
(gdb)
(gdb) p *tuple->t_data
$7 = {t_choice = {t_heap = {t_xmin = 160, t_xmax = 4294967295, t_field3 = {t_cid = 2249, t_xvac = 2249}}, t_datum = {
datum_len_ = 160, datum_typmod = -1, datum_typeid = 2249}}, t_ctid = {ip_blkid = {bi_hi = 65535, bi_lo = 65535},
ip_posid = 0}, t_infomask2 = 3, t_infomask = 2, t_hoff = 24 '/030', t_bits = 0x1e4f50f ""}
mtstate->mt_transition_capture 为NULL,无需处理相关信息
(gdb) p mtstate->mt_transition_capture $8 = (struct TransitionCaptureState *) 0x0 1783 if (mtstate->mt_oc_transition_capture != NULL) (gdb)
如需要,转换元组
1792 ConvertPartitionTupleSlot(proute->parent_child_tupconv_maps[partidx],
(gdb)
1798 Assert(mtstate != NULL);
(gdb)
1799 node = (ModifyTable *) mtstate->ps.plan;
(gdb) p *mtstate
$9 = {ps = {type = T_ModifyTableState, plan = 0x1e59838, state = 0x1e4daf8, ExecProcNode = 0x711056 <ExecModifyTable>,
ExecProcNodeReal = 0x711056 <ExecModifyTable>, instrument = 0x0, worker_instrument = 0x0, worker_jit_instrument = 0x0,
qual = 0x0, lefttree = 0x0, righttree = 0x0, initPlan = 0x0, subPlan = 0x0, chgParam = 0x0,
ps_ResultTupleSlot = 0x1e4ede8, ps_ExprContext = 0x0, ps_ProjInfo = 0x0, scandesc = 0x0}, operation = CMD_INSERT,
canSetTag = true, mt_done = false, mt_plans = 0x1e4e078, mt_nplans = 1, mt_whichplan = 0, resultRelInfo = 0x1e4dd48,
rootResultRelInfo = 0x0, mt_arowmarks = 0x1e4e098, mt_epqstate = {estate = 0x0, planstate = 0x0, origslot = 0x1e4e4e0,
plan = 0x1e59588, arowMarks = 0x0, epqParam = 0}, fireBSTriggers = false, mt_existing = 0x0, mt_excludedtlist = 0x0,
mt_conflproj = 0x0, mt_partition_tuple_routing = 0x1e4eb48, mt_transition_capture = 0x0, mt_oc_transition_capture = 0x0,
mt_per_subplan_tupconv_maps = 0x0}
返回slot,完成调用
(gdb) n 1800 if (node->onConflictAction == ONCONFLICT_UPDATE) (gdb) 1810 return slot; (gdb) 1811 }
到此，相信大家对“怎么理解PostgreSQL的分区表”有了更深的了解，不妨来实际操作一番吧！这里是亿速云网站，更多相关内容可以进入相关频道进行查询，关注我们，继续学习！
原创文章，作者：ItWorker，如若转载，请注明出处：https://blog.ytso.com/205021.html