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diff --git a/src/include/catalog/pg_amop.h b/src/include/catalog/pg_amop.h
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+/*-------------------------------------------------------------------------
+ *
+ * pg_amop.h
+ *	  definition of the "access method operator" system catalog (pg_amop)
+ *
+ * The amop table identifies the operators associated with each index operator
+ * family and operator class (classes are subsets of families).  An associated
+ * operator can be either a search operator or an ordering operator, as
+ * identified by amoppurpose.
+ *
+ * The primary key for this table is <amopfamily, amoplefttype, amoprighttype,
+ * amopstrategy>.  amoplefttype and amoprighttype are just copies of the
+ * operator's oprleft/oprright, ie its declared input data types.  The
+ * "default" operators for a particular opclass within the family are those
+ * with amoplefttype = amoprighttype = opclass's opcintype.  An opfamily may
+ * also contain other operators, typically cross-data-type operators.  All the
+ * operators within a family are supposed to be compatible, in a way that is
+ * defined by each individual index AM.
+ *
+ * We also keep a unique index on <amopopr, amoppurpose, amopfamily>, so that
+ * we can use a syscache to quickly answer questions of the form "is this
+ * operator in this opfamily, and if so what are its semantics with respect to
+ * the family?"  This implies that the same operator cannot be listed for
+ * multiple strategy numbers within a single opfamily, with the exception that
+ * it's possible to list it for both search and ordering purposes (with
+ * different strategy numbers for the two purposes).
+ *
+ * amopmethod is a copy of the owning opfamily's opfmethod field.  This is an
+ * intentional denormalization of the catalogs to buy lookup speed.
+ *
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/catalog/pg_amop.h
+ *
+ * NOTES
+ *	  The Catalog.pm module reads this file and derives schema
+ *	  information.
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef PG_AMOP_H
+#define PG_AMOP_H
+
+#include "catalog/genbki.h"
+#include "catalog/pg_amop_d.h"
+
+/* ----------------
+ *		pg_amop definition.  cpp turns this into
+ *		typedef struct FormData_pg_amop
+ * ----------------
+ */
+CATALOG(pg_amop,2602,AccessMethodOperatorRelationId)
+{
+	Oid			oid;			/* oid */
+
+	/* the index opfamily this entry is for */
+	Oid			amopfamily BKI_LOOKUP(pg_opfamily);
+
+	/* operator's left input data type */
+	Oid			amoplefttype BKI_LOOKUP(pg_type);
+
+	/* operator's right input data type */
+	Oid			amoprighttype BKI_LOOKUP(pg_type);
+
+	/* operator strategy number */
+	int16		amopstrategy;
+
+	/* is operator for 's'earch or 'o'rdering? */
+	char		amoppurpose BKI_DEFAULT(s);
+
+	/* the operator's pg_operator OID */
+	Oid			amopopr BKI_LOOKUP(pg_operator);
+
+	/* the index access method this entry is for */
+	Oid			amopmethod BKI_LOOKUP(pg_am);
+
+	/* ordering opfamily OID, or 0 if search op */
+	Oid			amopsortfamily BKI_DEFAULT(0) BKI_LOOKUP(pg_opfamily);
+} FormData_pg_amop;
+
+/* ----------------
+ *		Form_pg_amop corresponds to a pointer to a tuple with
+ *		the format of pg_amop relation.
+ * ----------------
+ */
+typedef FormData_pg_amop *Form_pg_amop;
+
+#ifdef EXPOSE_TO_CLIENT_CODE
+
+/* allowed values of amoppurpose: */
+#define AMOP_SEARCH		's'		/* operator is for search */
+#define AMOP_ORDER		'o'		/* operator is for ordering */
+
+#endif							/* EXPOSE_TO_CLIENT_CODE */
+
+#endif							/* PG_AMOP_H */