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1
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from .._stream import Stream, query_maker
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2
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3
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4
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def get_stream(cdb, stream):
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5
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if isinstance(stream, Stream):
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6
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return stream.path
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7
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elif stream.count("/") == 0:
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8
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return cdb.path + "/" + stream
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9
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elif stream.count("/") == 2:
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10
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return stream
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11
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else:
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12
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raise Exception("Stream '%s' invalid" % (stream, ))
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13
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14
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15
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class Merge(object):
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16
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"""Merge represents a query which allows to merge multiple streams into one
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17
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when reading, with all the streams merged together by increasing timestamp.
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18
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The merge query is used as a constructor-type object::
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19
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m = Merge(cdb)
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21
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m.addStream("mystream1",t1=time.time()-10)
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22
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m.addStream("mystream2",t1=time.time()-10)
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23
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result = m.run()
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24
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"""
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25
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26
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def __init__(self, cdb):
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27
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"""Given a ConnectorDB object, begins the construction of a Merge query"""
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28
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self.cdb = cdb
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29
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30
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self.query = []
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31
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32
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def addStream(self, stream, t1=None, t2=None, limit=None, i1=None, i2=None, transform=None):
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33
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"""Adds the given stream to the query construction. The function supports both stream
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34
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names and Stream objects."""
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35
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params = query_maker(t1, t2, limit, i1, i2, transform)
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36
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37
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params["stream"] = get_stream(self.cdb, stream)
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38
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39
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# Now add the stream to the query parameters
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40
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self.query.append(params)
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41
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42
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def run(self):
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43
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"""Runs the merge query, and returns the result"""
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44
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return self.cdb.db.query("merge", self.query)
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45
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connectordb /
connectordb-python
