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PG-156: Adding a placeholder replacement function for prepared statement 

When users set normalized_query to off and execute a prepared statement
user can see the actual value of parameters.

Reviewd By: Hamid Akhtar
pull/67/head
Martin Sun 2021-01-04 21:02:35 +08:00
parent 8691c51efb
commit 1e67e0b5bd
1 changed files with 102 additions and 0 deletions
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102
pg_stat_monitor.c
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@ -245,6 +245,8 @@ pg_stat_monitor_version(PG_FUNCTION_ARGS)
PG_RETURN_TEXT_P(cstring_to_text(BUILD_VERSION));
}
static char **get_params_text_list(const ParamListInfo paramlist);
static char *get_denormalized_query(const ParamListInfo paramlist, const char *query_text);
/*
* Post-parse-analysis hook: mark query with a queryId
@ -397,6 +399,7 @@ pgss_ExecutorEnd(QueryDesc *queryDesc)
float utime;
float stime;
uint64 queryId = queryDesc->plannedstmt->queryId;
const char *query_text;
if (queryId != UINT64CONST(0) && queryDesc->totaltime)
{
@ -409,6 +412,15 @@ pgss_ExecutorEnd(QueryDesc *queryDesc)
utime = TIMEVAL_DIFF(rusage_start.ru_utime, rusage_end.ru_utime);
stime = TIMEVAL_DIFF(rusage_start.ru_stime, rusage_end.ru_stime);
/*
* For a query with parameters if we want the actual query we denormalized it
* by replacing all the placeholders with actual parameter values.
*/
if(!PGSM_NORMALIZED_QUERY && queryDesc->params)
query_text = get_denormalized_query(queryDesc->params, queryDesc->sourceText);
else
query_text = queryDesc->sourceText;
if (PGSM_ENABLED == 1)
pgss_store(queryId,
queryDesc->sourceText,
@ -2596,3 +2608,93 @@ exit:
return buf_len;
}
/* transform parameters value from datum to string*/
static char **
get_params_text_list(const ParamListInfo paramlist)
{
StringInfoData buf;
int entry_num = paramlist->numParams;
int i;
char **params_text;
initStringInfo(&buf);
params_text = (char **)palloc0(sizeof(char *) * entry_num);
for(i = 0; i < entry_num; i++)
{
ParamExternData *param = &paramlist->params[i];
if (param->isnull || !OidIsValid(param->ptype))
{
appendStringInfoString(&buf, "NULL");
}
else
{
Oid typoutput;
bool typisvarlena;
char *pstring;
getTypeOutputInfo(param->ptype, &typoutput, &typisvarlena);
pstring = OidOutputFunctionCall(typoutput, param->value);
appendStringInfo(&buf, "%s",pstring);
}
/* assign memory space and add terminate symbol at the end of string*/
params_text[i] = (char *)palloc0(sizeof(char) * (buf.len + 1));
memcpy(params_text[i], buf.data, buf.len);
memset(params_text[i] + sizeof(char) * buf.len,'\0',sizeof(char));
/*clean the temp buffer*/
resetStringInfo(&buf);
}
return params_text;
}
/* denormalize the query, replace placeholder with actual value*/
static char *
get_denormalized_query(const ParamListInfo paramlist, const char *query_text)
{
int current_param;
int param_num;
int i;
char **param_text;
const char *cursor_ori;
StringInfoData result_buf;
param_text = get_params_text_list(paramlist);
param_num = paramlist->numParams;
current_param = 0;
cursor_ori = query_text;
initStringInfo(&result_buf);
while(*cursor_ori != '\0')
{
if(*cursor_ori != '$')
{
/* copy the origin query string to result*/
appendStringInfoChar(&result_buf,*cursor_ori);
cursor_ori++;
}
else
{
/* skip the placeholder */
cursor_ori++;
while(*cursor_ori >= '0' && *cursor_ori <= '9')
{
cursor_ori++;
}
/* replace the placeholder with actual value */
appendStringInfo(&result_buf,"%s",param_text[current_param++]);
}
}
/* free the query text array*/
for(i = 0; i < param_num; i++)
{
pfree(param_text[i]);
}
pfree(param_text);
return result_buf.data;
}