indexing

问题 I have what I thought was a simple query on a collection called 'email': const emailQuery = admin .firestore() .collection('email') .where('sendAt', '>=', new Date()) .where('orderId', '==', doc.orderId) .where('brandId', '==', doc.brandId); I'm receiving the error in the subject of this post, indicating that I need to create an index for this query. I've tried creating a couple for the relevant fields, but I'm unsure of why it's needed since only one field is ordered--and the error remains

问题 According to this FAQ on zlib.net it is possible to: access data randomly in a compressed stream I know about the module Bio.bgzf of Biopyton 1.60, which: supports reading and writing BGZF files (Blocked GNU Zip Format), a variant of GZIP with efficient random access, most commonly used as part of the BAM file format and in tabix. This uses Python’s zlib library internally, and provides a simple interface like Python’s gzip library. But for my use case I don't want to use that format.

问题 According to this FAQ on zlib.net it is possible to: access data randomly in a compressed stream I know about the module Bio.bgzf of Biopyton 1.60, which: supports reading and writing BGZF files (Blocked GNU Zip Format), a variant of GZIP with efficient random access, most commonly used as part of the BAM file format and in tabix. This uses Python’s zlib library internally, and provides a simple interface like Python’s gzip library. But for my use case I don't want to use that format.

问题 My aim is to use a composite index on the student table. The Student table will be inner joined onto the xyz table. I created my index on the student table as follows: CREATE INDEX email_phonenumber_student_idx ON student(phonenumber, email); When I run my query SELECT Phonenumber, email from student left join enrolment on enrolment.studentnumber = student.studentnumber where months_between(SYSDATE, dateofbirth)/12 >= 18 and enrolment.studentnumber is null and student.phonenumber =

问题 My aim is to use a composite index on the student table. The Student table will be inner joined onto the xyz table. I created my index on the student table as follows: CREATE INDEX email_phonenumber_student_idx ON student(phonenumber, email); When I run my query SELECT Phonenumber, email from student left join enrolment on enrolment.studentnumber = student.studentnumber where months_between(SYSDATE, dateofbirth)/12 >= 18 and enrolment.studentnumber is null and student.phonenumber =

问题 I have a Java method which creates an index on two fields from a Mongo collection. I should get the index info for the collection, then check if the name and fields of the index are correct. What is the cleanest way to write an integration test for this? Would it make sense to use a custom Hamcrest matcher to see if the index is in the collection? 回答1: In Spring With MongoTemplate#indexOps(String collection) you can fetch a List of IndexInfo , representing the indexes of the MongoDB

问题 I have a Java method which creates an index on two fields from a Mongo collection. I should get the index info for the collection, then check if the name and fields of the index are correct. What is the cleanest way to write an integration test for this? Would it make sense to use a custom Hamcrest matcher to see if the index is in the collection? 回答1: In Spring With MongoTemplate#indexOps(String collection) you can fetch a List of IndexInfo , representing the indexes of the MongoDB

问题 In Matlab I can find all non zero entries in a vector like this: >> v = [0 1 0 0 1] v = 0 1 0 0 1 >> indices = find(v) indices = 2 5 Assuming that my vector v can only have 0 and 1 values, what is a simple way to reproduce v from the indices vector? 回答1: you have to know what the shape v is (i.e. how long v is if it's a vector as in your example), but once you know that it's trivial: n = 5; v_reconstructed = zeros(1, n); v_reconstructed(indices) = 1; if you don't know how long v is then you

问题 I created a DatetimeIndex from a "date" column: sales.index = pd.DatetimeIndex(sales["date"]) Now the index looks as follows: DatetimeIndex(['2003-01-02', '2003-01-03', '2003-01-04', '2003-01-06', '2003-01-07', '2003-01-08', '2003-01-09', '2003-01-10', '2003-01-11', '2003-01-13', ... '2016-07-22', '2016-07-23', '2016-07-24', '2016-07-25', '2016-07-26', '2016-07-27', '2016-07-28', '2016-07-29', '2016-07-30', '2016-07-31'], dtype='datetime64[ns]', name='date', length=4393, freq=None) As you see

问题 I created an MS Access table using the following code: tbl := Database.CreateTableDef('English', 0, '', ''); try fld := tbl.CreateField('ID', dbLong, 0); fld.Attributes := dbAutoIncrField + dbFixedField; tbl.Fields.Append(fld); fld := tbl.CreateField('Content', dbText, 255); fld.Required := true; fld.AllowZeroLength := false; tbl.Fields.Append(fld); Database.TableDefs.Append(tbl); idx := tbl.CreateIndex('PrimaryKey'); idx.Fields.Append(idx.CreateField('ID', EmptyParam, EmptyParam)); idx