previous attempt was flawed (but maked by Reset() method)
new approach is to do this work in the Reset() method itself,
logically this is where it belongs.
but further we acknowledge that IndexInternalID []byte lifetime
lives beyond the TermFieldDoc, so another copy is made into
the DocumentMatch. Although this introduces yet another copy
the theory being tested is that it allows each of these
structuress to reuse memory without additional allocation.
when the term field reader is copying ID values out of the
kv store's iterator, it is already attempting to reuse the
term frequency row data structure. this change allows us
to also attempt to reuse the []byte allocated for previous
copies of the docid. we reset the slice length to zero
then copy the data into the existing slice, avoiding
new allocation and garbage collection in the cases where
there is already enough space
IndexInternalID is now []byte
this is still opaque, and should still work for any future
index implementations as it is a least common denominator
choice, all implementations must internally represent the
id as []byte at some point for storage to disk
index id's are now opaque (until finally returned to top-level user)
- the TermFieldDoc's returned by TermFieldReader no longer contain doc id
- instead they return an opaque IndexInternalID
- items returned are still in the "natural index order"
- but that is no longer guaranteed to be "doc id order"
- correct behavior requires that they all follow the same order
- but not any particular order
- new API FinalizeDocID which converts index internal ID's to public string ID
- APIs used internally which previously took doc id now take IndexInternalID
- that is DocumentFieldTerms() and DocumentFieldTermsForFields()
- however, APIs that are used externally do not reflect this change
- that is Document()
- DocumentIDReader follows the same changes, but this is less obvious
- behavior clarified, used to iterate doc ids, BUT NOT in doc id order
- method STILL available to iterate doc ids in range
- but again, you won't get them in any meaningful order
- new method to iterate actual doc ids from list of possible ids
- this was introduced to make the DocIDSearcher continue working
searchers now work with the new opaque index internal doc ids
- they return new DocumentMatchInternal (which does not have string ID)
scorerers also work with these opaque index internal doc ids
- they return DocumentMatchInternal (which does not have string ID)
collectors now also perform a final step of converting the final result
- they STILL return traditional DocumentMatch (with string ID)
- but they now also require an IndexReader (so that they can do the conversion)
at the time you create the term field reader, you can specify
that you don't need the term freq, the norm, or the term vectors
in that case, the index implementation can choose to not return
them in its subsequently returned values
this is advisory only, some simple implementations may ignore this
and continue to return the values anyway (as the current impl of
upside_down does today)
this change will allow future index implementations the
opportunity to do less work when it isn't required
The UpsideDownCouchTermFieldReader.Next() only needs the doc ID from
the key, so this change provides a specialized parseKDoc() method for
that optimization.
Additionally, fields in various structs are more 64-bit aligned, in an
attempt to reduce the invocations of runtime.typedmemmove() and
runtime.heapBitsBulkBarrier(), which the go compiler seems to
automatically insert to transparently handle misaligned data.
This optimization changes the index.TermFieldReader.Next() interface
API, adding an optional, pre-allocated *TermFieldDoc parameter, which
can help prevent garbage creation.
Before this change, upside down's reader would alloc a new
TermFrequencyRow on every Next(), which would be immediately
transformed into an index.TermFieldDoc{}. This change reuses a
pre-allocated TermFrequencyRow that's a field in the reader.
improvements uncovered some issues with how k/v data was copied
or not. to address this, kv abstraction layer now lets impl
specify if the bytes returned are safe to use after a reader
(or writer since writers are also readers) are closed
See index/store/KVReader - BytesSafeAfterClose() bool
false is the safe value if you're not sure
it will cause index impls to copy the data
Some kv impls already have created a copy a the C-api barrier
in which case they can safely return true.
Overall this yields ~25% speedup for searches with leveldb.
It yields ~10% speedup for boltdb.
Returning stored fields is now slower with boltdb, as previously
we were returning unsafe bytes.
this introduces disk format v4
now the summary rows for a term are stored in their own
"dictionary row" format, previously the same information
was stored in special term frequency rows
this now allows us to easily iterate all the terms for a field
in sorted order (useful for many other fuzzy data structures)
at the top-level of bleve you can now browse terms within a field
using the following api on the Index interface:
FieldDict(field string) (index.FieldDict, error)
FieldDictRange(field string, startTerm []byte, endTerm []byte) (index.FieldDict, error)
FieldDictPrefix(field string, termPrefix []byte) (index.FieldDict, error)
fixes#127
In the index/store package
introduce KVReader
creates snapshot
all read operations consistent from this snapshot
must close to release
introduce KVWriter
only one writer active
access to all operations
allows for consisten read-modify-write
must close to release
introduce AssociativeMerge operation on batch
allows efficient read-modify-write
for associative operations
used to consolidate updates to the term summary rows
saves 1 set and 1 get op per shared instance of term in field
In the index package
introduced an IndexReader
exposes a consisten snapshot of the index for searching
At top level
All searches now operate on a consisten snapshot of the index