release/src/router/mysql/storage/innobase/include/row0undo.h

   1 /******************************************************
   2 Row undo
   3
   4 (c) 1997 Innobase Oy
   5
   6 Created 1/8/1997 Heikki Tuuri
   7 *******************************************************/
   8
   9 #ifndef row0undo_h
  10 #define row0undo_h
  11
  12 #include "univ.i"
  13 #include "mtr0mtr.h"
  14 #include "trx0sys.h"
  15 #include "btr0types.h"
  16 #include "btr0pcur.h"
  17 #include "dict0types.h"
  18 #include "trx0types.h"
  19 #include "que0types.h"
  20 #include "row0types.h"
  21
  22 /************************************************************************
  23 Creates a row undo node to a query graph. */
  24
  25 undo_node_t*
  26 row_undo_node_create(
  27 /*=================*/
  28                                 /* out, own: undo node */
  29         trx_t*          trx,    /* in: transaction */
  30         que_thr_t*      parent, /* in: parent node, i.e., a thr node */
  31         mem_heap_t*     heap);  /* in: memory heap where created */
  32 /***************************************************************
  33 Looks for the clustered index record when node has the row reference.
  34 The pcur in node is used in the search. If found, stores the row to node,
  35 and stores the position of pcur, and detaches it. The pcur must be closed
  36 by the caller in any case. */
  37
  38 ibool
  39 row_undo_search_clust_to_pcur(
  40 /*==========================*/
  41                                 /* out: TRUE if found; NOTE the node->pcur
  42                                 must be closed by the caller, regardless of
  43                                 the return value */
  44         undo_node_t*    node);  /* in: row undo node */
  45 /***************************************************************
  46 Undoes a row operation in a table. This is a high-level function used
  47 in SQL execution graphs. */
  48
  49 que_thr_t*
  50 row_undo_step(
  51 /*==========*/
  52                                 /* out: query thread to run next or NULL */
  53         que_thr_t*      thr);   /* in: query thread */
  54
  55 /* A single query thread will try to perform the undo for all successive
  56 versions of a clustered index record, if the transaction has modified it
  57 several times during the execution which is rolled back. It may happen
  58 that the task is transferred to another query thread, if the other thread
  59 is assigned to handle an undo log record in the chain of different versions
  60 of the record, and the other thread happens to get the x-latch to the
  61 clustered index record at the right time.
  62         If a query thread notices that the clustered index record it is looking
  63 for is missing, or the roll ptr field in the record doed not point to the
  64 undo log record the thread was assigned to handle, then it gives up the undo
  65 task for that undo log record, and fetches the next. This situation can occur
  66 just in the case where the transaction modified the same record several times
  67 and another thread is currently doing the undo for successive versions of
  68 that index record. */
  69
  70 /* Undo node structure */
  71
  72 struct undo_node_struct{
  73         que_common_t    common; /* node type: QUE_NODE_UNDO */
  74         ulint           state;  /* node execution state */
  75         trx_t*          trx;    /* trx for which undo is done */
  76         dulint          roll_ptr;/* roll pointer to undo log record */
  77         trx_undo_rec_t* undo_rec;/* undo log record */
  78         dulint          undo_no;/* undo number of the record */
  79         ulint           rec_type;/* undo log record type: TRX_UNDO_INSERT_REC,
  80                                 ... */
  81         dulint          new_trx_id; /* trx id to restore to clustered index
  82                                 record */
  83         btr_pcur_t      pcur;   /* persistent cursor used in searching the
  84                                 clustered index record */
  85         dict_table_t*   table;  /* table where undo is done */
  86         ulint           cmpl_info;/* compiler analysis of an update */
  87         upd_t*          update; /* update vector for a clustered index
  88                                 record */
  89         dtuple_t*       ref;    /* row reference to the next row to handle */
  90         dtuple_t*       row;    /* a copy (also fields copied to heap) of the
  91                                 row to handle */
  92         dict_index_t*   index;  /* the next index whose record should be
  93                                 handled */
  94         mem_heap_t*     heap;   /* memory heap used as auxiliary storage for
  95                                 row; this must be emptied after undo is tried
  96                                 on a row */
  97 };
  98
  99 /* Execution states for an undo node */
 100 #define UNDO_NODE_FETCH_NEXT    1       /* we should fetch the next undo log
 101                                         record */
 102 #define UNDO_NODE_INSERT        2
 103 #define UNDO_NODE_MODIFY        3
 104
 105
 106 #ifndef UNIV_NONINL
 107 #include "row0undo.ic"
 108 #endif
 109
 110 #endif