In the normal course of operation, query trees will be serialized only if
they are stored as views or rules; and plan trees will be serialized only
if they get passed to parallel-query workers. This leaves an awful lot of
opportunity for bugs/oversights to not get detected, as indeed we've just
been reminded of the hard way.
To improve matters, this patch adds a new compile option
WRITE_READ_PARSE_PLAN_TREES, which is modeled on the longstanding option
COPY_PARSE_PLAN_TREES; but instead of passing all parse and plan trees
through copyObject, it passes them through nodeToString + stringToNode.
Enabling this option in a buildfarm animal or two will catch problems
at least for cases that are exercised by the regression tests.
A small problem with this idea is that readfuncs.c historically has
discarded location fields, on the reasonable grounds that parse
locations in a retrieved view are not relevant to the current query.
But doing that in WRITE_READ_PARSE_PLAN_TREES breaks pg_stat_statements,
and it could cause problems for future improvements that might try to
report error locations at runtime. To fix that, provide a variant
behavior in readfuncs.c that makes it restore location fields when
told to.
In passing, const-ify the string arguments of stringToNode and its
subsidiary functions, just because it annoyed me that they weren't
const already.
Discussion: https://postgr.es/m/17114.
1537138992@sss.pgh.pa.us
/* Static state for pg_strtok */
-static char *pg_strtok_ptr = NULL;
+static const char *pg_strtok_ptr = NULL;
+
+/* State flag that determines how readfuncs.c should treat location fields */
+#ifdef WRITE_READ_PARSE_PLAN_TREES
+bool restore_location_fields = false;
+#endif
/*
* stringToNode -
- * returns a Node with a given legal ASCII representation
+ * builds a Node tree from its string representation (assumed valid)
+ *
+ * restore_loc_fields instructs readfuncs.c whether to restore location
+ * fields rather than set them to -1. This is currently only supported
+ * in builds with the WRITE_READ_PARSE_PLAN_TREES debugging flag set.
*/
-void *
-stringToNode(char *str)
+static void *
+stringToNodeInternal(const char *str, bool restore_loc_fields)
{
- char *save_strtok;
void *retval;
+ const char *save_strtok;
+#ifdef WRITE_READ_PARSE_PLAN_TREES
+ bool save_restore_location_fields;
+#endif
/*
* We save and restore the pre-existing state of pg_strtok. This makes the
pg_strtok_ptr = str; /* point pg_strtok at the string to read */
+ /*
+ * If enabled, likewise save/restore the location field handling flag.
+ */
+#ifdef WRITE_READ_PARSE_PLAN_TREES
+ save_restore_location_fields = restore_location_fields;
+ restore_location_fields = restore_loc_fields;
+#endif
+
retval = nodeRead(NULL, 0); /* do the reading */
pg_strtok_ptr = save_strtok;
+#ifdef WRITE_READ_PARSE_PLAN_TREES
+ restore_location_fields = save_restore_location_fields;
+#endif
+
return retval;
}
+/*
+ * Externally visible entry points
+ */
+void *
+stringToNode(const char *str)
+{
+ return stringToNodeInternal(str, false);
+}
+
+#ifdef WRITE_READ_PARSE_PLAN_TREES
+
+void *
+stringToNodeWithLocations(const char *str)
+{
+ return stringToNodeInternal(str, true);
+}
+
+#endif
+
+
/*****************************************************************************
*
* the lisp token parser
* code should add backslashes to a string constant to ensure it is treated
* as a single token.
*/
-char *
+const char *
pg_strtok(int *length)
{
- char *local_str; /* working pointer to string */
- char *ret_str; /* start of token to return */
+ const char *local_str; /* working pointer to string */
+ const char *ret_str; /* start of token to return */
local_str = pg_strtok_ptr;
* any protective backslashes in the token are removed.
*/
char *
-debackslash(char *token, int length)
+debackslash(const char *token, int length)
{
char *result = palloc(length + 1);
char *ptr = result;
* Assumption: the ascii representation is legal
*/
static NodeTag
-nodeTokenType(char *token, int length)
+nodeTokenType(const char *token, int length)
{
NodeTag retval;
- char *numptr;
+ const char *numptr;
int numlen;
/*
* this should only be invoked from within a stringToNode operation).
*/
void *
-nodeRead(char *token, int tok_len)
+nodeRead(const char *token, int tok_len)
{
Node *result;
NodeTag type;
* never read executor state trees, either.
*
* Parse location fields are written out by outfuncs.c, but only for
- * possible debugging use. When reading a location field, we discard
+ * debugging use. When reading a location field, we normally discard
* the stored value and set the location field to -1 (ie, "unknown").
* This is because nodes coming from a stored rule should not be thought
* to have a known location in the current query's text.
+ * However, if restore_location_fields is true, we do restore location
+ * fields from the string. This is currently intended only for use by the
+ * WRITE_READ_PARSE_PLAN_TREES test code, which doesn't want to cause
+ * any change in the node contents.
*
*-------------------------------------------------------------------------
*/
/* And a few guys need only the pg_strtok support fields */
#define READ_TEMP_LOCALS() \
- char *token; \
+ const char *token; \
int length
/* ... but most need both */
token = pg_strtok(&length); /* get field value */ \
local_node->fldname = nullable_string(token, length)
-/* Read a parse location field (and throw away the value, per notes above) */
+/* Read a parse location field (and possibly throw away the value) */
+#ifdef WRITE_READ_PARSE_PLAN_TREES
+#define READ_LOCATION_FIELD(fldname) \
+ token = pg_strtok(&length); /* skip :fldname */ \
+ token = pg_strtok(&length); /* get field value */ \
+ local_node->fldname = restore_location_fields ? atoi(token) : -1
+#else
#define READ_LOCATION_FIELD(fldname) \
token = pg_strtok(&length); /* skip :fldname */ \
token = pg_strtok(&length); /* get field value */ \
(void) token; /* in case not used elsewhere */ \
local_node->fldname = -1 /* set field to "unknown" */
+#endif
/* Read a Node field */
#define READ_NODE_FIELD(fldname) \
Size length,
i;
int tokenLength;
- char *token;
+ const char *token;
Datum res;
char *s;
token = pg_strtok(&tokenLength); /* read the '[' */
if (token == NULL || token[0] != '[')
elog(ERROR, "expected \"[\" to start datum, but got \"%s\"; length = %zu",
- token ? (const char *) token : "[NULL]", length);
+ token ? token : "[NULL]", length);
if (typbyval)
{
token = pg_strtok(&tokenLength); /* read the ']' */
if (token == NULL || token[0] != ']')
elog(ERROR, "expected \"]\" to end datum, but got \"%s\"; length = %zu",
- token ? (const char *) token : "[NULL]", length);
+ token ? token : "[NULL]", length);
return res;
}
{
int tokenLength,
i;
- char *token;
+ const char *token;
AttrNumber *attr_vals;
if (numCols <= 0)
{
int tokenLength,
i;
- char *token;
+ const char *token;
Oid *oid_vals;
if (numCols <= 0)
{
int tokenLength,
i;
- char *token;
+ const char *token;
int *int_vals;
if (numCols <= 0)
{
int tokenLength,
i;
- char *token;
+ const char *token;
bool *bool_vals;
if (numCols <= 0)
Assert(pstate != NULL);
rte->rtekind = RTE_SUBQUERY;
- rte->relid = InvalidOid;
rte->subquery = subquery;
rte->alias = alias;
}
#endif
+ /*
+ * Currently, outfuncs/readfuncs support is missing for many raw parse
+ * tree nodes, so we don't try to implement WRITE_READ_PARSE_PLAN_TREES
+ * here.
+ */
+
TRACE_POSTGRESQL_QUERY_PARSE_DONE(query_string);
return raw_parsetree_list;
ShowUsage("REWRITER STATISTICS");
#ifdef COPY_PARSE_PLAN_TREES
- /* Optional debugging check: pass querytree output through copyObject() */
+ /* Optional debugging check: pass querytree through copyObject() */
{
List *new_list;
}
#endif
+#ifdef WRITE_READ_PARSE_PLAN_TREES
+ /* Optional debugging check: pass querytree through outfuncs/readfuncs */
+ {
+ List *new_list = NIL;
+ ListCell *lc;
+
+ /*
+ * We currently lack outfuncs/readfuncs support for most utility
+ * statement types, so only attempt to write/read non-utility queries.
+ */
+ foreach(lc, querytree_list)
+ {
+ Query *query = castNode(Query, lfirst(lc));
+
+ if (query->commandType != CMD_UTILITY)
+ {
+ char *str = nodeToString(query);
+ Query *new_query = stringToNodeWithLocations(str);
+
+ /*
+ * queryId is not saved in stored rules, but we must preserve
+ * it here to avoid breaking pg_stat_statements.
+ */
+ new_query->queryId = query->queryId;
+
+ new_list = lappend(new_list, new_query);
+ pfree(str);
+ }
+ else
+ new_list = lappend(new_list, query);
+ }
+
+ /* This checks both outfuncs/readfuncs and the equal() routines... */
+ if (!equal(new_list, querytree_list))
+ elog(WARNING, "outfuncs/readfuncs failed to produce equal parse tree");
+ else
+ querytree_list = new_list;
+ }
+#endif
+
if (Debug_print_rewritten)
elog_node_display(LOG, "rewritten parse tree", querytree_list,
Debug_pretty_print);
ShowUsage("PLANNER STATISTICS");
#ifdef COPY_PARSE_PLAN_TREES
- /* Optional debugging check: pass plan output through copyObject() */
+ /* Optional debugging check: pass plan tree through copyObject() */
{
PlannedStmt *new_plan = copyObject(plan);
}
#endif
+#ifdef WRITE_READ_PARSE_PLAN_TREES
+ /* Optional debugging check: pass plan tree through outfuncs/readfuncs */
+ {
+ char *str;
+ PlannedStmt *new_plan;
+
+ str = nodeToString(plan);
+ new_plan = stringToNodeWithLocations(str);
+ pfree(str);
+
+ /*
+ * equal() currently does not have routines to compare Plan nodes, so
+ * don't try to test equality here. Perhaps fix someday?
+ */
+#ifdef NOT_USED
+ /* This checks both outfuncs/readfuncs and the equal() routines... */
+ if (!equal(new_plan, plan))
+ elog(WARNING, "outfuncs/readfuncs failed to produce an equal plan tree");
+ else
+#endif
+ plan = new_plan;
+ }
+#endif
+
/*
* Print plan if debugging.
*/
/*
* nodes/{readfuncs.c,read.c}
*/
-extern void *stringToNode(char *str);
+extern void *stringToNode(const char *str);
+#ifdef WRITE_READ_PARSE_PLAN_TREES
+extern void *stringToNodeWithLocations(const char *str);
+#endif
extern struct Bitmapset *readBitmapset(void);
extern uintptr_t readDatum(bool typbyval);
extern bool *readBoolCols(int numCols);
#include "nodes/nodes.h"
+/*
+ * variable in read.c that needs to be accessible to readfuncs.c
+ */
+#ifdef WRITE_READ_PARSE_PLAN_TREES
+extern bool restore_location_fields;
+#endif
+
/*
* prototypes for functions in read.c (the lisp token parser)
*/
-extern char *pg_strtok(int *length);
-extern char *debackslash(char *token, int length);
-extern void *nodeRead(char *token, int tok_len);
+extern const char *pg_strtok(int *length);
+extern char *debackslash(const char *token, int length);
+extern void *nodeRead(const char *token, int tok_len);
/*
* prototypes for functions in readfuncs.c
*/
/* #define COPY_PARSE_PLAN_TREES */
+/*
+ * Define this to force all parse and plan trees to be passed through
+ * outfuncs.c/readfuncs.c, to facilitate catching errors and omissions in
+ * those modules.
+ */
+/* #define WRITE_READ_PARSE_PLAN_TREES */
+
/*
* Define this to force all raw parse trees for DML statements to be scanned
* by raw_expression_tree_walker(), to facilitate catching errors and
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