summaryrefslogtreecommitdiffstats
path: root/src/include/access/toast_helper.h
diff options
context:
space:
mode:
Diffstat (limited to 'src/include/access/toast_helper.h')
-rw-r--r--src/include/access/toast_helper.h116
1 files changed, 116 insertions, 0 deletions
diff --git a/src/include/access/toast_helper.h b/src/include/access/toast_helper.h
new file mode 100644
index 0000000..05104ce
--- /dev/null
+++ b/src/include/access/toast_helper.h
@@ -0,0 +1,116 @@
+/*-------------------------------------------------------------------------
+ *
+ * toast_helper.h
+ * Helper functions for table AMs implementing compressed or
+ * out-of-line storage of varlena attributes.
+ *
+ * Copyright (c) 2000-2021, PostgreSQL Global Development Group
+ *
+ * src/include/access/toast_helper.h
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#ifndef TOAST_HELPER_H
+#define TOAST_HELPER_H
+
+#include "utils/rel.h"
+
+/*
+ * Information about one column of a tuple being toasted.
+ *
+ * NOTE: toast_action[i] can have these values:
+ * ' ' default handling
+ * TYPSTORAGE_PLAIN already processed --- don't touch it
+ * TYPSTORAGE_EXTENDED incompressible, but OK to move off
+ *
+ * NOTE: toast_attr[i].tai_size is only made valid for varlena attributes with
+ * toast_action[i] different from TYPSTORAGE_PLAIN.
+ */
+typedef struct
+{
+ struct varlena *tai_oldexternal;
+ int32 tai_size;
+ uint8 tai_colflags;
+ char tai_compression;
+} ToastAttrInfo;
+
+/*
+ * Information about one tuple being toasted.
+ */
+typedef struct
+{
+ /*
+ * Before calling toast_tuple_init, the caller must initialize the
+ * following fields. Each array must have a length equal to
+ * ttc_rel->rd_att->natts. The tts_oldvalues and tts_oldisnull fields
+ * should be NULL in the case of an insert.
+ */
+ Relation ttc_rel; /* the relation that contains the tuple */
+ Datum *ttc_values; /* values from the tuple columns */
+ bool *ttc_isnull; /* null flags for the tuple columns */
+ Datum *ttc_oldvalues; /* values from previous tuple */
+ bool *ttc_oldisnull; /* null flags from previous tuple */
+
+ /*
+ * Before calling toast_tuple_init, the caller should set tts_attr to
+ * point to an array of ToastAttrInfo structures of a length equal to
+ * tts_rel->rd_att->natts. The contents of the array need not be
+ * initialized. ttc_flags also does not need to be initialized.
+ */
+ uint8 ttc_flags;
+ ToastAttrInfo *ttc_attr;
+} ToastTupleContext;
+
+/*
+ * Flags indicating the overall state of a TOAST operation.
+ *
+ * TOAST_NEEDS_DELETE_OLD indicates that one or more old TOAST datums need
+ * to be deleted.
+ *
+ * TOAST_NEEDS_FREE indicates that one or more TOAST values need to be freed.
+ *
+ * TOAST_HAS_NULLS indicates that nulls were found in the tuple being toasted.
+ *
+ * TOAST_NEEDS_CHANGE indicates that a new tuple needs to built; in other
+ * words, the toaster did something.
+ */
+#define TOAST_NEEDS_DELETE_OLD 0x0001
+#define TOAST_NEEDS_FREE 0x0002
+#define TOAST_HAS_NULLS 0x0004
+#define TOAST_NEEDS_CHANGE 0x0008
+
+/*
+ * Flags indicating the status of a TOAST operation with respect to a
+ * particular column.
+ *
+ * TOASTCOL_NEEDS_DELETE_OLD indicates that the old TOAST datums for this
+ * column need to be deleted.
+ *
+ * TOASTCOL_NEEDS_FREE indicates that the value for this column needs to
+ * be freed.
+ *
+ * TOASTCOL_IGNORE indicates that the toaster should not further process
+ * this column.
+ *
+ * TOASTCOL_INCOMPRESSIBLE indicates that this column has been found to
+ * be incompressible, but could be moved out-of-line.
+ */
+#define TOASTCOL_NEEDS_DELETE_OLD TOAST_NEEDS_DELETE_OLD
+#define TOASTCOL_NEEDS_FREE TOAST_NEEDS_FREE
+#define TOASTCOL_IGNORE 0x0010
+#define TOASTCOL_INCOMPRESSIBLE 0x0020
+
+extern void toast_tuple_init(ToastTupleContext *ttc);
+extern int toast_tuple_find_biggest_attribute(ToastTupleContext *ttc,
+ bool for_compression,
+ bool check_main);
+extern void toast_tuple_try_compression(ToastTupleContext *ttc, int attribute);
+extern void toast_tuple_externalize(ToastTupleContext *ttc, int attribute,
+ int options);
+extern void toast_tuple_cleanup(ToastTupleContext *ttc);
+
+extern void toast_delete_external(Relation rel, Datum *values, bool *isnull,
+ bool is_speculative);
+
+#endif