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v4.0
    v4.0

    Expression | Filter

    Expression

    Expression is a syntactical arithmetic combination of Operator and Operand. Every expression has a value.

    • Operator: conditional operators, logical operators, numeric operators (see the next chapter for operators and their precedence)

    • Operand: constant, alias, function, current schema, current property

    Operand Examples Example Expressions
    Constant 1,"abc", "2020-01-01 0:0:0" 1+3*2
    Alias nodes,edges,paths nodes.level,edges.amount < 2000
    Function now(),count(nodes),year("2022-04-12") year(edges.time) > 2020
    Current schema this.@ @ == "card",@product
    Current property this._id,this.name level != 2

    (Nodes, edges, paths listed above are the aliases of Edge, Node, and Path; "this" from the aliases of current node and edge can be omitted in most cases)

    • Value: NODE,EDGE,PATH,ATTR(number, time, string, True/False),ARRAY,TABLE

    Filter

    Ultipa filter is an expression encapsulated in curly bracket { }, which acquires the property and schema of node/edge by calling the alias. The expression produces true if the current node/edge meets the filtering rules. The filtering of node/edge is supported by all Ultipa query operations.

    • The conversion between value of filter and True/False:
    Before Conversion Converted
    Not 0 True
    0 False
    True 1
    False 0

    When converting string, datetime to True/False: it will be converted to False if first character is 0, otherwise True. When converting timestamp to Ture/False, for instance, "1970-01-01 08:00:00" should be False, otherwise True.

    Implementation Specification Example
    Common filtering To filter current node or edge in any types of queries {time > "2022-02-24 07:00:00"}
    In-step filtering To filter current node, current edge, the previous node, and the previous edge with system alias prev_n and prev_e in template query {time > prev_e.time}
    Full-text filtering To filter all the texts in properties of current node and edge in any tpes of queries by full-text index {~content contains "graph ultra* database"}

    (The "time" is a property name, "content" is the full-text index for a property)

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