My scenario is something like this:
I have a students database. I want to query all the students who were either
`absent` or `present` during a particular `date-range`.
For example:
Student "X" was `absent` between dates:
Jan 1, 2015 and Jan 15, 2015
Feb 13, 2015 and Feb 16, 2015
March 19, 2015 and March 25, 2015
Also "X" was `present` between dates:
Jan 25, 2015 and Jan 30, 2015
Feb 1, 2015 and Feb 12, 2015
(Other days were either school holidays or the teacher was either
lazy/forgot to take the attendance ;)
If the date range was only a single-valued field then this approach would
work:
http://stackoverflow.com/questions/25246204/solr-query-for-documents-whose-from-to-date-range-contains-the-user-input.
I have multiple-date ranges for each student, so this would not work for my
use-case.
Lucent 5.0 has support for `DateRangeField`
(http://lucene.apache.org/solr/5_0_0/solr-core/index.html?org/apache/solr/schema/DateRangeField.html
) which is perfect for my use-case, but I cannot upgrade to 5.0 yet! I am on
Lucene 4.1.0. David Smiley had mentioned that it would be ported to 4.x but
I guess it never happened (https://issues.apache.org/jira/browse/SOLR-6103,
I can try porting this patch my-self but I would like to know what it takes
and opinions)
So basically, I need to maintain relationship between the start and end
dates for each of the `state`s (absence or presence). So I thought I would
need to index the fields as pairs as mentioned here:
http://grokbase.com/t/lucene/solr-user/128r96vwz6/how-do-i-represent-a-group-of-customer-key-value-pairs
I guess my schema would look like:
<fieldType name="tdate" class="solr.TrieDateField" omitNorms="true"
precisionStep="6" positionIncrementGap="0"/>
<field name="state" type="string" indexed="true" stored="true"
multiValued="true"/>
<dynamicField name="presenceStartTime_*" type="tdate" indexed="true"
stored="true"/>
<dynamicField name="presenceEndTime_*" type="tdate" indexed="true"
stored="true"/>
<dynamicField name="absenceStartTime_*" type="tdate" indexed="true"
stored="true"/>
<dynamicField name="absenceEndTime_*" type="tdate" indexed="true"
stored="true"/>
**Question #1:** Does this look correct ?
**Question #2:** What are the ramifications if I use `tlong` instead of
`tdate` ? My `tlong` type looks like this:
<fieldType name="tlong" class="solr.TrieLongField" precisionStep="8"
omitNorms="true" positionIncrementGap="0"/>
**Question #3:** So in this case, for the query: "get all the students who
were absent between a date range" would the query would look something
similar to this ?
(state: absent) AND
(absenceStartTime1: givenLowerBoundDate) AND
(absenceStartTime2: givenLowerBoundDate) AND
(absenceStartTime3: givenLowerBoundDate) AND
(absenceEndTime1: givenUpperBoundDate) AND
(absenceEndTime2: givenUpperBoundDate) AND
(absenceEndTime3: givenUpperBoundDate)
This would work only if I knew that there were 3 dates in which the student
was absent before hand and there's no way to query all dynamic fields with
wild-cards according to
http://stackoverflow.com/questions/6213184/solr-search-query-for-dynamic-fields-indexed
**Question #4:** The workaround mentioned in one of the answers in that
question did not look terrible but seemed a bit complicated. Is there a
better alternative for solving this problem in Solr ?
Of course, I would be highly interested in any other better approaches.
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