This is a parquet file reader made by lisp. You can read headers of FileMetaData, ColumnMetadata, ChunkData but not all headers. Currently, this project is only support a SNAPPY compression codesc.
For more parquet headers, please read a parquet-format specs. (https://github.com/apache/parquet-format).
For example, some parquet files is located in "tests/tpch/".
load-parquet will return a data-parquet-table class. This class has a column-names, dataset of the loaded parquet file.
(load-parquet "./tests/tpch/region.parquet")
(print (load-parquet "./tests/tpch/region.parquet"))
A defalut limit is 10.
(show-data (load-parquet "./tests/tpch/region.parquet"))
(show-data (load-parquet "./tests/tpch/part.parquet") :limit 9)
(get-column-names (load-parquet "./tests/tpch/region.parquet"))
(get-data (load-parquet "./tests/tpch/region.parquet"))
(get-data-by-name (load-parquet "./tests/tpch/region.parquet") "r_regionkey")
(get-data-by-name (load-parquet "./tests/tpch/region.parquet") "r_comment")
(get-num-cols (load-parquet "./tests/tpch/region.parquet"))
(get-num-rows (load-parquet "./tests/tpch/region.parquet"))
;; means
(sample-mean (get-data-by-name (load-parquet "./tests/tpch/region.parquet") "r_regionkey"))
;; min
(min-item-from (get-data-by-name (load-parquet "./tests/tpch/region.parquet") "r_regionkey"))
;; max
(max-item-from (get-data-by-name (load-parquet "./tests/tpch/region.parquet") "r_regionkey"))
;; quantile
(quantile-of-ordered-seq (sort (get-data-by-name (load-parquet "./tests/tpch/region.parquet") "r_regionkey") #'<) 0.25)
(quantile-of-ordered-seq (sort (get-data-by-name (load-parquet "./tests/tpch/region.parquet") "r_regionkey") #'<) 0.75)
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