[tag=DT] | [lemma=on] □
[tag=DT] | [lemma=on] □ □
[tag=DT] | [lemma=on] (□ | □)
When specifying merge sort operators , the current operator and both referenced operators must return boolean ; the SORT1 operator must have both input datatypes equal to the current operator 's left argument type , and the SORT2 operator must have both input datatypes equal to the current operator 's right argument type . Please Report Problems : If your system is not automatically recognized by configure and you have to do this , please send email to scrappy@hub.org with the output of the program . These operators must be named ' <' and '> ' ; you do not have any choice in the matter , since there is no provision for specifying them explicitly . Hence , both mechanisms permit users to trojan horse others with relative impunity . But this is after the rule system and will be discussed later . What this means is that a join using " = " between interval fields would yield different results if implemented as a hash join than if implemented another way , because a large fraction of the pairs that should match will hash to different values and will never be compared by the hash join . The exec saves one layer of shell under the postmaster process so the parent is init.In RedHat Linux add a file / etc / rc.d / init.d / postgres.init which is based on the example in contrib / linux / . DeWitt created the Space-Based Radar software engineering team , led the authoring of the Software Acquisition Master Plan , established programmatic software risk plans , and is the contracting officer 's technical representative for all software issues to both prime system contractors . Using update rules , this can include write access to tables . So , both data types must be capable of being fully ordered , and the join operator must be one that can only succeed for pairs of values that fall at the " same place " in the sort order . Writing new restriction selectivity estimation functions is far beyond the scope of this chapter , but fortunately you can usually just use one of the system 's standard estimators for many of your own operators .