/*
* Drop one or more objects.
*
* We don't currently handle all object types here. Relations,for example,* require special handling,because (for example) indexes have additional
* locking requirements.
*
* We look up all the objects first,and then delete them in a single
* performMultipleDeletions() call. This avoids unnecessary DROP RESTRICT
* errors if there are dependencies between them.
*/
void
RemoveObjects(DropStmt *stmt)
/*
* Dispatch function for DropStmt
*/
static void
ExecDropStmt(DropStmt *stmt,bool isTopLevel)
{
switch (stmt->removeType)
{
case OBJECT_INDEX:
if (stmt->concurrent)
PreventTransactionChain(isTopLevel,"DROP INDEX CONCURRENTLY");
/* fall through */
case OBJECT_TABLE:
case OBJECT_SEQUENCE:
case OBJECT_VIEW:
case OBJECT_MATVIEW:
case OBJECT_FOREIGN_TABLE:
RemoveRelations(stmt);
break;
default:
RemoveObjects(stmt);
break;
}
}
/*
* standard_ProcessUtility itself deals only with utility commands for
* which we do not provide event trigger support. Commands that do have
* such support are passed down to ProcessUtilitySlow,which contains the
* necessary infrastructure for such triggers.
*
* This division is not just for performance: it's critical that the
* event trigger code not be invoked when doing START TRANSACTION for
* example,because we might need to refresh the event trigger cache,* which requires being in a valid transaction.
*/
void
standard_ProcessUtility(Node *parsetree,const char *queryString,ProcessUtilityContext context,ParamListInfo params,DestReceiver *dest,char *completionTag)
/*
* ProcessUtility
* general utility function invoker
*
* parsetree: the parse tree for the utility statement
* queryString: original source text of command
* context: identifies source of statement (toplevel client command,* non-toplevel client command,subcommand of a larger utility command)
* params: parameters to use during execution
* dest: where to send results
* completionTag: points to a buffer of size COMPLETION_TAG_BUFSIZE
* in which to store a command completion status string.
*
* Notes: as of PG 8.4,caller MUST supply a queryString; it is not
* allowed anymore to pass NULL. (If you really don't have source text,* you can pass a constant string,perhaps "(query not available)".)
*
* completionTag is only set nonempty if we want to return a nondefault status.
*
* completionTag may be NULL if caller doesn't want a status string.
*/
void
ProcessUtility(Node *parsetree,char *completionTag)
@H_301_0@
@H_301_0@详细调用栈如下：
#0 ExecDropStmt (stmt=0x17e9b40,isTopLevel=1 '\001') at utility.c:1349
#1 0x0000000000759457 in ProcessUtilitySlow (parsetree=0x17e9b40,queryString=0x17e90b0 "drop table t1;",context=PROCESS_UTILITY_TOPLEVEL,params=0x0,dest=0x17e9ea0,completionTag=0x7fff06aee670 "") at utility.c:1296
#2 0x0000000000758849 in standard_ProcessUtility (parsetree=0x17e9b40,completionTag=0x7fff06aee670 "") at utility.c:792
#3 0x0000000000757c88 in ProcessUtility (parsetree=0x17e9b40,completionTag=0x7fff06aee670 "") at utility.c:310
#4 0x0000000000756e92 in PortalRunUtility (portal=0x1822d70,utilityStmt=0x17e9b40,isTopLevel=1 '\001',completionTag=0x7fff06aee670 "")
at pquery.c:1187
#5 0x0000000000757048 in PortalRunMulti (portal=0x1822d70,altdest=0x17e9ea0,completionTag=0x7fff06aee670 "") at pquery.c:1318
#6 0x000000000075661c in PortalRun (portal=0x1822d70,count=9223372036854775807,completionTag=0x7fff06aee670 "") at pquery.c:816
#7 0x0000000000750944 in exec_simple_query (query_string=0x17e90b0 "drop table t1;") at postgres.c:1045
#8 0x0000000000754967 in PostgresMain (argc=1,argv=0x1784148,dbname=0x1784130 "wzy",username=0x1784110 "xiaochu.yh") at postgres.c:4004
#9 0x00000000006e80ba in BackendRun (port=0x17a3e00) at postmaster.c:4117
#10 0x00000000006e77fd in BackendStartup (port=0x17a3e00) at postmaster.c:3791
#11 0x00000000006e41b2 in ServerLoop () at postmaster.c:1570
#12 0x00000000006e392e in PostmasterMain (argc=3,argv=0x1783380) at postmaster.c:1223
#13 0x000000000064d3d3 in main (argc=3,argv=0x1783380) at main.c:225
Portal，入口的意思。Postgre中，Portal是个抽象概念，它表示一个正在运行或可运行Query的执行状态。
@H_301_0@
@H_301_0@对于可以生成执行计划的sql语句（planable sql），都通过ProcessQuery来处理；对于不能生成执行计划的sql语句，取名为命令型sql（Command sql），都通过PortalRunUtility来处理。 @H_301_0@
@H_301_0@
@H_301_0@参考： @H_301_0@1. gdb使用http://blog.chinaunix.net/uid-20788636-id-1841301.html @H_301_0@2. postgre编译安装启动http://blog.chinaunix.net/uid-11161675-id-2903295.html @H_301_0@3. postgre官方文档http://www.postgresql.org/docs/current/static/index.html @H_301_0@4. 如何做postgre源码分析http://blog.csdn.net/anzelin_ruc/article/details/8622770 原文链接：https://www.f2er.com/postgresql/195375.html
