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Diffstat (limited to 'src/include/access/relscan.h')
| -rw-r--r-- | src/include/access/relscan.h | 176 |
1 files changed, 176 insertions, 0 deletions
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h new file mode 100644 index 0000000..6f02588 --- /dev/null +++ b/src/include/access/relscan.h @@ -0,0 +1,176 @@ +/*------------------------------------------------------------------------- + * + * relscan.h + * POSTGRES relation scan descriptor definitions. + * + * + * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group + * Portions Copyright (c) 1994, Regents of the University of California + * + * src/include/access/relscan.h + * + *------------------------------------------------------------------------- + */ +#ifndef RELSCAN_H +#define RELSCAN_H + +#include "access/htup_details.h" +#include "access/itup.h" +#include "port/atomics.h" +#include "storage/buf.h" +#include "storage/spin.h" +#include "utils/relcache.h" + + +struct ParallelTableScanDescData; + +/* + * Generic descriptor for table scans. This is the base-class for table scans, + * which needs to be embedded in the scans of individual AMs. + */ +typedef struct TableScanDescData +{ + /* scan parameters */ + Relation rs_rd; /* heap relation descriptor */ + struct SnapshotData *rs_snapshot; /* snapshot to see */ + int rs_nkeys; /* number of scan keys */ + struct ScanKeyData *rs_key; /* array of scan key descriptors */ + + /* + * Information about type and behaviour of the scan, a bitmask of members + * of the ScanOptions enum (see tableam.h). + */ + uint32 rs_flags; + + struct ParallelTableScanDescData *rs_parallel; /* parallel scan + * information */ + +} TableScanDescData; +typedef struct TableScanDescData *TableScanDesc; + +/* + * Shared state for parallel table scan. + * + * Each backend participating in a parallel table scan has its own + * TableScanDesc in backend-private memory, and those objects all contain a + * pointer to this structure. The information here must be sufficient to + * properly initialize each new TableScanDesc as workers join the scan, and it + * must act as a information what to scan for those workers. + */ +typedef struct ParallelTableScanDescData +{ + Oid phs_relid; /* OID of relation to scan */ + bool phs_syncscan; /* report location to syncscan logic? */ + bool phs_snapshot_any; /* SnapshotAny, not phs_snapshot_data? */ + Size phs_snapshot_off; /* data for snapshot */ +} ParallelTableScanDescData; +typedef struct ParallelTableScanDescData *ParallelTableScanDesc; + +/* + * Shared state for parallel table scans, for block oriented storage. + */ +typedef struct ParallelBlockTableScanDescData +{ + ParallelTableScanDescData base; + + BlockNumber phs_nblocks; /* # blocks in relation at start of scan */ + slock_t phs_mutex; /* mutual exclusion for setting startblock */ + BlockNumber phs_startblock; /* starting block number */ + pg_atomic_uint64 phs_nallocated; /* number of blocks allocated to + * workers so far. */ +} ParallelBlockTableScanDescData; +typedef struct ParallelBlockTableScanDescData *ParallelBlockTableScanDesc; + +/* + * Base class for fetches from a table via an index. This is the base-class + * for such scans, which needs to be embedded in the respective struct for + * individual AMs. + */ +typedef struct IndexFetchTableData +{ + Relation rel; +} IndexFetchTableData; + +/* + * We use the same IndexScanDescData structure for both amgettuple-based + * and amgetbitmap-based index scans. Some fields are only relevant in + * amgettuple-based scans. + */ +typedef struct IndexScanDescData +{ + /* scan parameters */ + Relation heapRelation; /* heap relation descriptor, or NULL */ + Relation indexRelation; /* index relation descriptor */ + struct SnapshotData *xs_snapshot; /* snapshot to see */ + int numberOfKeys; /* number of index qualifier conditions */ + int numberOfOrderBys; /* number of ordering operators */ + struct ScanKeyData *keyData; /* array of index qualifier descriptors */ + struct ScanKeyData *orderByData; /* array of ordering op descriptors */ + bool xs_want_itup; /* caller requests index tuples */ + bool xs_temp_snap; /* unregister snapshot at scan end? */ + + /* signaling to index AM about killing index tuples */ + bool kill_prior_tuple; /* last-returned tuple is dead */ + bool ignore_killed_tuples; /* do not return killed entries */ + bool xactStartedInRecovery; /* prevents killing/seeing killed + * tuples */ + + /* index access method's private state */ + void *opaque; /* access-method-specific info */ + + /* + * In an index-only scan, a successful amgettuple call must fill either + * xs_itup (and xs_itupdesc) or xs_hitup (and xs_hitupdesc) to provide the + * data returned by the scan. It can fill both, in which case the heap + * format will be used. + */ + IndexTuple xs_itup; /* index tuple returned by AM */ + struct TupleDescData *xs_itupdesc; /* rowtype descriptor of xs_itup */ + HeapTuple xs_hitup; /* index data returned by AM, as HeapTuple */ + struct TupleDescData *xs_hitupdesc; /* rowtype descriptor of xs_hitup */ + + ItemPointerData xs_heaptid; /* result */ + bool xs_heap_continue; /* T if must keep walking, potential + * further results */ + IndexFetchTableData *xs_heapfetch; + + bool xs_recheck; /* T means scan keys must be rechecked */ + + /* + * When fetching with an ordering operator, the values of the ORDER BY + * expressions of the last returned tuple, according to the index. If + * xs_recheckorderby is true, these need to be rechecked just like the + * scan keys, and the values returned here are a lower-bound on the actual + * values. + */ + Datum *xs_orderbyvals; + bool *xs_orderbynulls; + bool xs_recheckorderby; + + /* parallel index scan information, in shared memory */ + struct ParallelIndexScanDescData *parallel_scan; +} IndexScanDescData; + +/* Generic structure for parallel scans */ +typedef struct ParallelIndexScanDescData +{ + Oid ps_relid; + Oid ps_indexid; + Size ps_offset; /* Offset in bytes of am specific structure */ + char ps_snapshot_data[FLEXIBLE_ARRAY_MEMBER]; +} ParallelIndexScanDescData; + +struct TupleTableSlot; + +/* Struct for storage-or-index scans of system tables */ +typedef struct SysScanDescData +{ + Relation heap_rel; /* catalog being scanned */ + Relation irel; /* NULL if doing heap scan */ + struct TableScanDescData *scan; /* only valid in storage-scan case */ + struct IndexScanDescData *iscan; /* only valid in index-scan case */ + struct SnapshotData *snapshot; /* snapshot to unregister at end of scan */ + struct TupleTableSlot *slot; +} SysScanDescData; + +#endif /* RELSCAN_H */ |