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The values in most_common_vals, if present, are omitted from this histogram calculation. (This expression is null if the expression data type does not have a \u003c operator or if the most_common_vals list accounts for the entire population.)","description_zh":"用于将表达式的值划分为若干组的值列表，各组所含值的数量近似相等。如果存在 most_common_vals，其中的值会被直方图计算所忽略（如果表达式的数据类型没有一个\u003c操作符或者 most_common_vals 列表覆盖了全部值，则此列为 NULL）","documented":true,"documented_name":"histogram_bounds","hidden":false,"name":"histogram_bounds","not_null":false,"references":"","type":"anyarray","type_modifier":-1,"type_oid":2277,"zh_from":"same-version-manual"},{"array_dimensions":0,"attnum":14,"description":"Statistical correlation between physical row ordering and logical ordering of the expression values. This ranges from -1 to +1. When the value is near -1 or +1, an index scan on the expression will be estimated to be cheaper than when it is near zero, due to reduction of random access to the disk. (This expression is null if the expression's data type does not have a \u003c operator.)","description_zh":"物理行顺序和表达式值逻辑顺序之间的统计相关性。其范围从-1 到+1。当值接近-1 或+1 时，在表达式上的一个索引扫描被估计为比值接近 0 时的代价更低，因为这种情况减少了对磁盘的随机访问（如果表达式的数据类型不具有一个\u003c操作符，则此列为 NULL）","documented":true,"documented_name":"correlation","hidden":false,"name":"correlation","not_null":false,"references":"","type":"float4","type_modifier":-1,"type_oid":700,"zh_from":"same-version-manual"},{"array_dimensions":0,"attnum":15,"description":"A list of non-null element values most often appearing within values of the expression. (Null for scalar types.)","description_zh":"表达式值内最常出现的非 NULL 元素值的列表（对于标量类型为 NULL）。","documented":true,"documented_name":"most_common_elems","hidden":false,"name":"most_common_elems","not_null":false,"references":"","type":"anyarray","type_modifier":-1,"type_oid":2277,"zh_from":"same-version-manual"},{"array_dimensions":0,"attnum":16,"description":"A list of the frequencies of the most common element values, i.e., the fraction of rows containing at least one instance of the given value. Two or three additional values follow the per-element frequencies; these are the minimum and maximum of the preceding per-element frequencies, and optionally the frequency of null elements. (Null when most_common_elems is.)","description_zh":"高频元素值的频率列表，即至少包含一次给定值的行所占的比例。所有逐元素频率之后还有两个或三个附加值：前述逐元素频率的最小值和最大值，以及可选的 NULL 元素频率（当 most_common_elems 为 NULL 时，此列为 NULL）。","documented":true,"documented_name":"most_common_elem_freqs","hidden":false,"name":"most_common_elem_freqs","not_null":false,"references":"","type":"float4[]","type_modifier":-1,"type_oid":1021,"zh_from":"same-version-manual"},{"array_dimensions":0,"attnum":17,"description":"A histogram of the counts of distinct non-null element values within the values of the expression, followed by the average number of distinct non-null elements. (Null for scalar types.)","description_zh":"各表达式值中不同非 NULL 元素的数量的直方图，后面跟随该数量的平均值（对于标量类型为 NULL）。","documented":true,"documented_name":"elem_count_histogram","hidden":false,"name":"elem_count_histogram","not_null":false,"references":"","type":"float4[]","type_modifier":-1,"type_oid":1021,"zh_from":"same-version-manual"}],"description":"The view pg_stats_ext_exprs provides access to information about all expressions included in extended statistics objects, combining information stored in the pg_statistic_ext and pg_statistic_ext_data catalogs. This view allows access only to rows of pg_statistic_ext and pg_statistic_ext_data that correspond to tables the user owns, and therefore it is safe to allow public read access to this view.\n\npg_stats_ext_exprs is also designed to present the information in a more readable format than the underlying catalogs — at the cost that its schema must be extended whenever the structure of statistics in pg_statistic_ext changes."}},"RequestedLocale":"en","Fallback":false,"Versions":["14","15","16","17","18","19","20"],"Locales":["en","zh-Hans"],"Signatures":null,"Spellings":null,"SQLState":null,"Evidence":null}