Question

我有一个很大的表，我想从最低的id开始，循环遍历并过滤，直到得到1000行，然后再返回。

所以我的函数getFilteredItems将进行一些过滤，然后返回1000行。它有一个latestItemId参数，因此它将在特定的id之后占用1000行。然后，getJournalistTopicItems调用getFilteredItems，该函数甚至可以过滤更多内容。大多数情况下，此功能将过滤掉所有行，因此我想循环直到所有过滤完成后最终获得1000行。

我在sql方面特别是超级菜鸟，尤其是postgres，所以这一切可能都是矫kill过正或完全错误，但这是我到目前为止所做的。

CREATE OR REPLACE FUNCTION getJournalistTopicItems() RETURNS  TEXT AS $$
DECLARE
    currentCount INTEGER = 0;
    currentItemIds int[];
    latestItem INTEGER = 0;
BEGIN       
        WHILE currentCount < 1000 LOOP      
            WITH fItems AS (
                SELECT * FROM getFilteredItems(latestItem)
            )
            SELECT fi.itemId, ift.content
            FROM fItems fi
            INNER JOIN journalistitems ji ON ji.itemid = fi.itemid       
            INNER JOIN itemfulltexts ift ON ji.itemid = ift.itemid
            INNER JOIN journalists j ON j.id = ji.journalistid
            INNER JOIN contacts c ON c.journalistid = j.id
              WHERE  c.isprivate = FALSE
              AND c.disabled = FALSE
              AND c.verificationstatus = 1;           

            currentItemIds := array_append(fi.itemId);
            currentCount := array_length(currentItemIds);
            SELECT latestItemId INTO latestItem FROM getFilteredItems(latestItem) limit 1;

        END LOOP;
        RETURN array_to_string(currentItemIds);
END;
$$ LANGUAGE plpgsql;

getFilteredItems函数如下所示：

CREATE OR REPLACE FUNCTION getFilteredItems(latestId INTEGER) RETURNS TABLE(
    latestItemId integer,
    itemid integer
) AS $$
BEGIN
    RETURN QUERY
    WITH fItems AS(select i.id 
        from items i
        inner join articlemetadatas am on am.itemid = i.id
        where NOT EXISTS (SELECT 1 FROM journalistitemcategories jic WHERE jic.itemid = i.id)
          AND NOT EXISTS (SELECT 1 FROM topicitemwords tw WHERE tw.itemid = i.id)
          AND i.languagecode in ('sv')
          AND am.contentprotected != 0
          AND i.id > latestId
         limit 1000)
         SELECT (SELECT id FROM fItems order by id desc limit 1), fItems.id FROM fItems;
END;
$$ LANGUAGE plpgsql;

调用getJournalistTopicItems时出现的错误是：

ERROR:  query has no destination for result data
HINT:  If you want to discard the results of a SELECT, use PERFORM instead.
CONTEXT:  PL/pgSQL function getjournalisttopicitems() line 8 at SQL statement
SQL state: 42601

最新更新：

CREATE OR REPLACE FUNCTION getJournalistTopicItems() RETURNS  SETOF TEXT AS $func$
DECLARE
    idarr int[];
    idmed int[];
    latestItem INTEGER = 0;
    currentCount INTEGER = 0;
BEGIN       
        WHILE currentCount < 1000 LOOP      
            WITH fItems AS (
                SELECT * FROM getFilteredItems(latestItem)
            )
            SELECT fi.itemId, ift.content
            FROM fItems fi
            INNER JOIN journalistitems ji ON ji.itemid = fi.itemid       
            INNER JOIN itemfulltexts ift ON ji.itemid = ift.itemid
            INNER JOIN journalists j ON j.id = ji.journalistid
            INNER JOIN contacts c ON c.journalistid = j.id
              WHERE  c.isprivate = FALSE
              AND c.disabled = FALSE
              AND c.verificationstatus = 1;           

            idmed := (select array_agg(itemId) from fItems);
            idarr := (select idarr || idmed);
            currentCount := (select array_length(currentCount, int));
            latestItem := (select latestItem FROM getFilteredItems(latestItem) limit 1);        

        END LOOP;
        RETURN QUERY SELECT array_to_string(idarr, ',');
END;
$func$ language plpgsql;

循环功能，直到达到postgres的限制

0 个答案: