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db_include/utils/queryjumble.h

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+/*-------------------------------------------------------------------------
+ *
+ * queryjumble.h
+ *	  Query normalization and fingerprinting.
+ *
+ * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * IDENTIFICATION
+ *	  src/include/utils/queryjumble.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef QUERYJUBLE_H
+#define QUERYJUBLE_H
+
+#include "nodes/parsenodes.h"
+
+#define JUMBLE_SIZE				1024	/* query serialization buffer size */
+
+/*
+ * Struct for tracking locations/lengths of constants during normalization
+ */
+typedef struct LocationLen
+{
+	int			location;		/* start offset in query text */
+	int			length;			/* length in bytes, or -1 to ignore */
+} LocationLen;
+
+/*
+ * Working state for computing a query jumble and producing a normalized
+ * query string
+ */
+typedef struct JumbleState
+{
+	/* Jumble of current query tree */
+	unsigned char *jumble;
+
+	/* Number of bytes used in jumble[] */
+	Size		jumble_len;
+
+	/* Array of locations of constants that should be removed */
+	LocationLen *clocations;
+
+	/* Allocated length of clocations array */
+	int			clocations_buf_size;
+
+	/* Current number of valid entries in clocations array */
+	int			clocations_count;
+
+	/* highest Param id we've seen, in order to start normalization correctly */
+	int			highest_extern_param_id;
+} JumbleState;
+
+/* Values for the compute_query_id GUC */
+enum ComputeQueryIdType
+{
+	COMPUTE_QUERY_ID_OFF,
+	COMPUTE_QUERY_ID_ON,
+	COMPUTE_QUERY_ID_AUTO
+};
+
+/* GUC parameters */
+extern int	compute_query_id;
+
+
+extern const char *CleanQuerytext(const char *query, int *location, int *len);
+extern JumbleState *JumbleQuery(Query *query, const char *querytext);
+extern void EnableQueryId(void);
+
+extern bool query_id_enabled;
+
+/*
+ * Returns whether query identifier computation has been enabled, either
+ * directly in the GUC or by a module when the setting is 'auto'.
+ */
+static inline bool
+IsQueryIdEnabled(void)
+{
+	if (compute_query_id == COMPUTE_QUERY_ID_OFF)
+		return false;
+	if (compute_query_id == COMPUTE_QUERY_ID_ON)
+		return true;
+	return query_id_enabled;
+}
+
+#endif							/* QUERYJUMBLE_H */