trx0rec.h

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/** @file include/trx0rec.h
 Transaction undo log record
 
 Created 3/26/1996 Heikki Tuuri
 *******************************************************/
 
#ifndef trx0rec_h
#define trx0rec_h
 
#include "univ.i"
 
#include "data0data.h"
#include "dict0types.h"
#include "lob0undo.h"
#include "mtr0mtr.h"
#include "page0types.h"
#include "rem0types.h"
#include "row0log.h"
#include "row0types.h"
#include "trx0types.h"
 
#ifndef UNIV_HOTBACKUP
#include "que0types.h"
 
/** Copies the undo record to the heap.
@param[in]      undo_page       Undo Page
@param[in]      undo_offset     offset of the undo record in the page
@param[in]      heap            heap where copied
@return copy of undo log record */
static inline trx_undo_rec_t *trx_undo_rec_copy(const page_t *undo_page,
                                                uint32_t undo_offset,
                                                mem_heap_t *heap);
 
/** Reads the undo log record type.
 @return record type */
static inline ulint trx_undo_rec_get_type(
    const trx_undo_rec_t *undo_rec); /*!< in: undo log record */
/** Reads from an undo log record the record compiler info.
 @return compiler info */
static inline ulint trx_undo_rec_get_cmpl_info(
    const trx_undo_rec_t *undo_rec); /*!< in: undo log record */
/** Returns true if an undo log record contains an extern storage field.
 @return true if extern */
static inline bool trx_undo_rec_get_extern_storage(
    const trx_undo_rec_t *undo_rec); /*!< in: undo log record */
/** Reads the undo log record number.
 @return undo no */
static inline undo_no_t trx_undo_rec_get_undo_no(
    const trx_undo_rec_t *undo_rec); /*!< in: undo log record */
 
/** Reads from an undo log record the table ID
@param[in]      undo_rec        Undo log record
@return the table ID */
[[nodiscard]] table_id_t trx_undo_rec_get_table_id(
    const trx_undo_rec_t *undo_rec);
 
/** Builds a row reference from an undo log record.
 @return pointer to remaining part of undo record */
const byte *trx_undo_rec_get_row_ref(
    const byte *ptr,     /*!< in: remaining part of a copy of an undo log
                   record, at the start of the row reference;
                   NOTE that this copy of the undo log record must
                   be preserved as long as the row reference is
                   used, as we do NOT copy the data in the
                   record! */
    dict_index_t *index, /*!< in: clustered index */
    dtuple_t **ref,      /*!< out, own: row reference */
    mem_heap_t *heap);   /*!< in: memory heap from which the memory
                         needed is allocated */
/** Reads from an undo log update record the system field values of the old
 version.
 @return remaining part of undo log record after reading these values */
const byte *trx_undo_update_rec_get_sys_cols(
    const byte *ptr,      /*!< in: remaining part of undo
                          log record after reading
                          general parameters */
    trx_id_t *trx_id,     /*!< out: trx id */
    roll_ptr_t *roll_ptr, /*!< out: roll ptr */
    ulint *info_bits);    /*!< out: info bits state */
 
struct type_cmpl_t;
 
/** Builds an update vector based on a remaining part of an undo log record.
@param[in] ptr Remaining part in update undo log record, after reading the row
reference. NOTE that this copy of the undo log record must be preserved as long
as the update vector is used, as we do NOT copy the data in the record!
@param[in] index Clustered index.
@param[in] type TRX_UNDO_UPD_EXIST_REC, TRX_UNDO_UPD_DEL_REC, or
TRX_UNDO_DEL_MARK_REC; in the last case, only trx id and roll ptr fields are
added to the update vector.
@param[in] trx_id Transaction id from this undo record.
@param[in] roll_ptr Roll pointer from this undo record.
@param[in] info_bits Info bits from this undo record.
@param[in] heap Memory heap from which the memory needed is allocated.
@param[out] upd Update vector.
@param[out] lob_undo LOB undo information.
@param[out] type_cmpl Type compilation info.
@return remaining part of the record, NULL if an error detected, which
means that the record is corrupted. */
const byte *trx_undo_update_rec_get_update(
    const byte *ptr, const dict_index_t *index, ulint type, trx_id_t trx_id,
    roll_ptr_t roll_ptr, ulint info_bits, mem_heap_t *heap, upd_t **upd,
    lob::undo_vers_t *lob_undo, type_cmpl_t &type_cmpl);
 
/** Builds a partial row from an update undo log record, for purge.
 It contains the columns which occur as ordering in any index of the table.
 Any missing columns are indicated by col->mtype == DATA_MISSING.
 @return pointer to remaining part of undo record */
[[nodiscard]] const byte *trx_undo_rec_get_partial_row(
    const byte *ptr,     /*!< in: remaining part in update undo log
                         record of a suitable type, at the start of
                         the stored index columns;
                         NOTE that this copy of the undo log record must
                         be preserved as long as the partial row is
                         used, as we do NOT copy the data in the
                         record! */
    dict_index_t *index, /*!< in: clustered index */
    dtuple_t **row,      /*!< out, own: partial row */
    bool ignore_prefix,  /*!< in: flag to indicate if we
                   expect blob prefixes in undo. Used
                   only in the assertion. */
    mem_heap_t *heap);   /*!< in: memory heap from which the memory
                        needed is allocated */
/** Writes information to an undo log about an insert, update, or a delete
 marking of a clustered index record. This information is used in a rollback of
 the transaction and in consistent reads that must look to the history of this
 transaction.
 @return DB_SUCCESS or error code */
[[nodiscard]] dberr_t trx_undo_report_row_operation(
    ulint flags,                 /*!< in: if BTR_NO_UNDO_LOG_FLAG bit is
                                 set, does nothing */
    ulint op_type,               /*!< in: TRX_UNDO_INSERT_OP or
                                 TRX_UNDO_MODIFY_OP */
    que_thr_t *thr,              /*!< in: query thread */
    dict_index_t *index,         /*!< in: clustered index */
    const dtuple_t *clust_entry, /*!< in: in the case of an insert,
                                 index entry to insert into the
                                 clustered index, otherwise NULL */
    const upd_t *update,         /*!< in: in the case of an update,
                                 the update vector, otherwise NULL */
    ulint cmpl_info,             /*!< in: compiler info on secondary
                                 index updates */
    const rec_t *rec,            /*!< in: case of an update or delete
                                 marking, the record in the clustered
                                 index, otherwise NULL */
    const ulint *offsets,        /*!< in: rec_get_offsets(rec) */
    roll_ptr_t *roll_ptr);       /*!< out: rollback pointer to the
                                inserted undo log record,
                                0 if BTR_NO_UNDO_LOG
                                flag was specified */
 
/** status bit used for trx_undo_prev_version_build() */
 
/** TRX_UNDO_PREV_IN_PURGE tells trx_undo_prev_version_build() that it
is being called purge view and we would like to get the purge record
even it is in the purge view (in normal case, it will return without
fetching the purge record */
constexpr uint32_t TRX_UNDO_PREV_IN_PURGE = 0x1;
 
/** This tells trx_undo_prev_version_build() to fetch the old value in
the undo log (which is the after image for an update) */
constexpr uint32_t TRX_UNDO_GET_OLD_V_VALUE = 0x2;
 
/** Build a previous version of a clustered index record. The caller must hold
a latch on the index page of the clustered index record.
If the vrow passed to this function is not null, then this function will store
information about virtual columns from the requested version in vrow, unless the
change did not affect any secondary index nor ordering field of clustered index
(the change has UPD_NODE_NO_ORD_CHANGE flag) in which case the requested
information can not be reconstructed from undo log, and the caller may assume
that the (virtual) columns of secondary index have the same values they have in
the more recent version (the one `rec` comes from).
Equivalently, if the vrow is not returned, it is either because it was not
requested, or not available due to UPD_NODE_NO_ORD_CHANGE.
Obviously vrow is also not set in case rec is the oldest version in history,
in which case we also set old_vers to NULL.
@param[in]      index_rec       clustered index record in the index tree
@param[in]      index_mtr       mtr which contains the latch to index_rec page
                                and purge_view
@param[in]      rec             version of a clustered index record
@param[in]      index           clustered index
@param[in,out]  offsets         rec_get_offsets(rec, index)
@param[in]      heap            memory heap from which the memory needed is
                                allocated
@param[out]     old_vers        previous version, or NULL if rec is the first
                                inserted version, or if history data has been
                                deleted
@param[in]      v_heap          memory heap used to create vrow dtuple if it is
                                not yet created. This heap diffs from "heap"
                                above in that it could be
                                prebuilt->old_vers_heap for selection
@param[out]     vrow            virtual column info, if any
@param[in]      v_status        status determine if it is going into this
                                function by purge thread or not. And if we read
                                "after image" of undo log has been rebuilt
@param[in]      lob_undo        LOB undo information.
@retval true if previous version was built, or if it was an insert or the table
has been rebuilt
@retval false if the previous version is earlier than purge_view, or being
purged, which means that it may have been removed */
bool trx_undo_prev_version_build(const rec_t *index_rec, mtr_t *index_mtr,
                                 const rec_t *rec, const dict_index_t *index,
                                 ulint *offsets, mem_heap_t *heap,
                                 rec_t **old_vers, mem_heap_t *v_heap,
                                 const dtuple_t **vrow, ulint v_status,
                                 lob::undo_vers_t *lob_undo);
 
#endif /* !UNIV_HOTBACKUP */
/** Parses a redo log record of adding an undo log record.
 @return end of log record or NULL */
const byte *trx_undo_parse_add_undo_rec(
    const byte *ptr,     /*!< in: buffer */
    const byte *end_ptr, /*!< in: buffer end */
    page_t *page);       /*!< in: page or NULL */
 
/** Parses a redo log record of erasing of an undo page end.
@param[in,out]  ptr      Buffer.
@param[in,out]  end_ptr  Buffer end.
@param[in,out]  page     Page or nullptr.
@param[in,out]  mtr      MTR or nullptr.
@return end of log record or nullptr */
const byte *trx_undo_parse_erase_page_end(const byte *ptr, const byte *end_ptr,
                                          page_t *page, mtr_t *mtr);
 
/** Read from an undo log record a non-virtual column value.
@param[in,out]  ptr             pointer to remaining part of the undo record
@param[in,out]  field           stored field
@param[in,out]  len             length of the field, or UNIV_SQL_NULL
@param[in,out]  orig_len        original length of the locally stored part
of an externally stored column, or 0
@return remaining part of undo log record after reading these values */
const byte *trx_undo_rec_get_col_val(const byte *ptr, const byte **field,
                                     ulint *len, ulint *orig_len);
 
/** Read virtual column value from undo log
@param[in]      table           the table
@param[in]      ptr             undo log pointer
@param[in,out]  row             the dtuple to fill
@param[in]      in_purge        called by purge thread
@param[in]      online          true if this is from online DDL log
@param[in]      col_map         online rebuild column map
@param[in,out]  heap            memory heap to keep value when necessary */
void trx_undo_read_v_cols(const dict_table_t *table, const byte *ptr,
                          const dtuple_t *row, bool in_purge, bool online,
                          const ulint *col_map, mem_heap_t *heap);
 
/** Read virtual column index from undo log or online log if the log
contains such info, and in the undo log case, verify the column is
still indexed, and output its position
@param[in]      table           the table
@param[in]      ptr             undo log pointer
@param[in]      first_v_col     if this is the first virtual column, which
                                has the version marker
@param[in,out]  is_undo_log     this function is used to parse both undo log,
                                and online log for virtual columns. So
                                check to see if this is undo log. When
                                first_v_col is true, is_undo_log is output,
                                when first_v_col is false, is_undo_log is input
@param[in,out]  field_no        the column number
@return remaining part of undo log record after reading these values */
const byte *trx_undo_read_v_idx(const dict_table_t *table, const byte *ptr,
                                bool first_v_col, bool *is_undo_log,
                                ulint *field_no);
 
#ifndef UNIV_HOTBACKUP
 
/* Types of an undo log record: these have to be smaller than 16, as the
compilation info multiplied by 16 is ORed to this value in an undo log
record */
 
/** fresh insert into clustered index */
constexpr uint32_t TRX_UNDO_INSERT_REC = 11;
/** update of a non-delete-marked  record */
constexpr uint32_t TRX_UNDO_UPD_EXIST_REC = 12;
/** update of a delete marked record to a not delete marked record; also the
fields of the record can change */
constexpr uint32_t TRX_UNDO_UPD_DEL_REC = 13;
/* delete marking of a record; fields do not change */
constexpr uint32_t TRX_UNDO_DEL_MARK_REC = 14;
/** compilation info is multiplied by this and ORed to the type above */
constexpr uint32_t TRX_UNDO_CMPL_INFO_MULT = 16;
/** If this bit is set in type_cmpl,  then the undo log record has support for
 partial update of BLOBs. Also to  make the undo log format extensible,
 introducing a new flag next to the  type_cmpl flag. */
constexpr uint32_t TRX_UNDO_MODIFY_BLOB = 64;
/* This bit can be ORed to type_cmpl to denote that we updated external storage
 fields: used by purge to free the external storage */
constexpr uint32_t TRX_UNDO_UPD_EXTERN = 128;
 
/** Operation type flags used in trx_undo_report_row_operation */
constexpr uint32_t TRX_UNDO_INSERT_OP = 1;
constexpr uint32_t TRX_UNDO_MODIFY_OP = 2;
 
/** The type and compilation info flag in the undo record for update.
For easier understanding let the 8 bits be numbered as
7, 6, 5, 4, 3, 2, 1, 0. */
struct type_cmpl_t {
  type_cmpl_t() : m_flag(0) {}
 
  const byte *read(const byte *ptr) {
    m_flag = mach_read_from_1(ptr);
    return (ptr + 1);
  }
 
  ulint type_info() {
    /* Get 0-3 */
    return (m_flag & 0x0F);
  }
 
  ulint cmpl_info() {
    /* Get bits 5 and 4 */
    return ((m_flag >> 4) & 0x03);
  }
 
  /** Is an LOB updated by this update operation.
  @return true if LOB is updated, false otherwise. */
  bool is_lob_updated() {
    /* Check if bit 7 is set. */
    return (m_flag & TRX_UNDO_UPD_EXTERN);
  }
 
  /** Does the undo log record contains information about LOB partial
  update vector.
  @return true if undo contains LOB update info. */
  bool is_lob_undo() const {
    /* Check if bit 6 is set. */
    return (m_flag & TRX_UNDO_MODIFY_BLOB);
  }
 
 private:
  uint8_t m_flag;
};
 
/** Reads from an undo log record the general parameters.
 @return remaining part of undo log record after reading these values */
const byte *trx_undo_rec_get_pars(
    trx_undo_rec_t *undo_rec, /*!< in: undo log record */
    ulint *type,              /*!< out: undo record type:
                              TRX_UNDO_INSERT_REC, ... */
    ulint *cmpl_info,         /*!< out: compiler info, relevant only
                              for update type records */
    bool *updated_extern,     /*!< out: true if we updated an
                              externally stored fild */
    undo_no_t *undo_no,       /*!< out: undo log record number */
    table_id_t *table_id,     /*!< out: table id */
    type_cmpl_t &type_cmpl);  /*!< out: type compilation info. */
 
/** Get the max free space of undo log by assuming it's a fresh new page
and the free space doesn't count for the undo log header too. */
size_t trx_undo_max_free_space();
 
/** Decide if the following undo log record is a multi-value virtual column
@param[in]     undo_rec        undo log record
@return true if this is a multi-value virtual column log, otherwise false */
bool trx_undo_rec_is_multi_value(const byte *undo_rec);
 
/** Read from an undo log record of a multi-value virtual column.
@param[in]      ptr     pointer to remaining part of the undo record
@param[in,out]  field   stored field, nullptr if the col is no longer
                        indexed or existing, in the latter case,
                        this function will only skip the log
@param[in,out]  heap    memory heap
@return remaining part of undo log record after reading these values */
const byte *trx_undo_rec_get_multi_value(const byte *ptr, dfield_t *field,
                                         mem_heap_t *heap);
#include "trx0rec.ic"
 
#endif /* !UNIV_HOTBACKUP */
 
#endif /* trx0rec_h */