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Diffstat (limited to 'src/include/access/toast_helper.h')
-rw-r--r-- | src/include/access/toast_helper.h | 116 |
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 |