如何为范围查询编写Aerospike流UDF

Question

我为一个范围查询编写了一个Stream UDF，但它没有正常工作。你知道如何用lua设置很多过滤器吗？

查询：

SELECT id1, id2, link_type, visibility, data, time, version FROM linktable
WHERE id1 = <id1> AND
  link_type = <link_type> AND
  time >= <minTime> AND
  time <= <maxTimestamp> AND
  visibility = VISIBILITY_DEFAULT
ORDER BY time DESC LIMIT <offset>, <limit>;

调用此lua函数的Java代码：

stmt = new Statement();
stmt.setNamespace(dbid);
stmt.setSetName("links");
stmt.setIndexName("time");
stmt.setFilters(Filter.range("time", minTimestamp, maxTimestamp));
stmt.setAggregateFunction("linkbench", "check_id1", Value.get(id1));
stmt.setAggregateFunction("linkbench", "check_linktype", Value.get(link_type));
resultSet = client.queryAggregate(null, stmt, "linkbench", "check_visibility", Value.get(VISIBILITY_DEFAULT));

Lua Script：

local function map_links(record)
    -- Add user and password to returned map.
    -- Could add other record bins here as well.
    return record.id2
end

function check_id1(stream,id1)
    local function filter_id1(record)
        return record.id1 == id1
    end
    return stream : filter(filter_id1) : map(map_links)
end

function check_linktype(stream,link_type)
    local function filter_linktype(record)
        return record.link_type == link_type
    end
    return stream : filter(filter_linktype) : map(map_links)
end

function check_visibility(stream,visibility)
    local function filter_visibility(record)
        return record.visibility == visibility
    end
    return stream : filter(filter_visibility) : map(map_links)
end

知道如何为所有查询限制编写过滤器吗？

谢谢！

Answer 1

不支持多个聚合功能。必须合并聚合和过滤功能。

function combined_aggregation(stream,id1,link_type,visibility)
    local function combined_filter(record)
        return record.id1 == id1 and 
               record.link_type == link_type and
               record.visibility == visibility
    end
    return stream : filter(combined_filter) : map(map_links)
end

Answer 2

由于predicate filter a PredExp是正确的方法，因此完全避免使用Lua以获得更好的性能和可伸缩性。

查看Java客户端的examples类及其C，以构建复杂的过滤器。谓词过滤目前也适用于C#，Go和个客户。