diff options
Diffstat (limited to 'sql/item.h')
| -rw-r--r-- | sql/item.h | 35 |
1 files changed, 24 insertions, 11 deletions
diff --git a/sql/item.h b/sql/item.h index dcfe1b58122..28856842b99 100644 --- a/sql/item.h +++ b/sql/item.h @@ -1,4 +1,4 @@ -/* Copyright (c) 2000, 2010 Oracle and/or its affiliates. All rights reserved. +/* Copyright (c) 2000, 2011, Oracle and/or its affiliates. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -574,10 +574,17 @@ public: Field *make_string_field(TABLE *table); virtual bool fix_fields(THD *, Item **); /* - should be used in case where we are sure that we do not need + This method should be used in case where we are sure that we do not need complete fix_fields() procedure. - */ - inline void quick_fix_field() { fixed= 1; } + Usually this method is used by the optimizer when it has to create a new + item out of other already fixed items. For example, if the optimizer has + to create a new Item_func for an inferred equality whose left and right + parts are already fixed items. In some cases the optimizer cannot use + directly fixed items as the arguments of the created functional item, + but rather uses intermediate type conversion items. Then the method is + supposed to be applied recursively. + */ + virtual inline void quick_fix_field() { fixed= 1; } /* Function returns 1 on overflow and -1 on fatal errors */ int save_in_field_no_warnings(Field *field, bool no_conversions); virtual int save_in_field(Field *field, bool no_conversions); @@ -1043,11 +1050,11 @@ public: virtual bool set_no_const_sub(uchar *arg) { return FALSE; } virtual Item *replace_equal_field(uchar * arg) { return this; } /* - Check if an expression value depends on the current timezone. Used by - partitioning code to reject timezone-dependent expressions in a - (sub)partitioning function. + Check if an expression value has allowed arguments, like DATE/DATETIME + for date functions. Also used by partitioning code to reject + timezone-dependent expressions in a (sub)partitioning function. */ - virtual bool is_timezone_dependent_processor(uchar *bool_arg) + virtual bool check_valid_arguments_processor(uchar *bool_arg) { return FALSE; } @@ -3123,11 +3130,10 @@ class Item_cache: public Item_basic_constant protected: Item *example; table_map used_table_map; - /* - Field that this object will get value from. This is set/used by + /** + Field that this object will get value from. This is used by index-based subquery engines to detect and remove the equality injected by IN->EXISTS transformation. - For all other uses of Item_cache, cached_field doesn't matter. */ Field *cached_field; enum enum_field_types cached_field_type; @@ -3189,6 +3195,13 @@ public: return trace_unsupported_by_check_vcol_func_processor("cache"); } + /** + If this item caches a field value, return pointer to underlying field. + + @return Pointer to field, or NULL if this is not a cache for a field value. + */ + Field* field() { return cached_field; } + virtual void store(Item *item); virtual bool cache_value()= 0; }; |