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Β· 4 min read
Trent Hauck

In addition to launching the public preview of Exome last week, we've also made some updates to Exon.

First, Exon now supports Hive style partitions. This means you can augment your table definitions with partition information. This is useful because:

  1. It allows you to augment your file schemas with additional metadata. For example, the experiment date, or the sample type.
  2. It allows you to query subsets of your data without having to scan the entire table. For example, you can query only the data from a specific sample.

Second, ExonR has been updated to support a SQL session allowing you to create and query tables directly from R, rather than just scan entire files.

Finally, as more of an administrative note, we've added a GitHub Sponsors page. If you find our open source software useful, please consider sponsoring us. Thanks!

Table Partitions​

Table partitions are encoded in the file path when you store the data and additionally in the table definition.

For example, say you had a bunch of S3 objects at:


You could create a table definition like:

LOCATION 's3://bucket/fasta_table'

Then you could query the data like:

FROM fasta_table
WHERE sample = 'sampleA'

And what happens is super useful, Exon will subset the files it scans based on the predicated and augment the FASTA table with the sample column.

So you end up with something like:


Moreover, this makes it straight forward to join with other data. For example, if you had a table of sample metadata:

LOCATION 's3://bucket/sample_metadata/'

You could join the two tables like:

FROM fasta_table
JOIN sample_metadata
ON fasta_table.sample = sample_metadata.sample

Thus simplifying your analysis by allowing deeper analysis without complex ETL. Moveover, you can add additional partitions without having to reprocess your data, just add the new files to the appropriate location and Exon will pick them up.

ExonR SQL Session​

R is R first programming language love πŸ˜‰. So we continue to build out the R interface to Exon. The latest addition is the ability to work with Exon sessions directly from R. Previously you were only able to scan entire files, but now you can create and query tables directly from R.

For example, you can create a table like, then query it through DuckDB or just directly through a DataFrame.

First create the table from a local file.


session <- ExonRSessionContext$new()
session$execute("CREATE EXTERNAL TABLE gene_annotations STORED AS GFF LOCATION 'annotations.gff'")

rdf <- session$sql("SELECT seqname, source, type, start, \"end\", score, strand, phase FROM gene_annotations")

Then for DuckDB, convert the result to an Arrow table and then load it into DuckDB.

arrow_table <- rdf$to_arrow()

con <- dbConnect(duckdb::duckdb())

arrow::to_duckdb(arrow_table, table_name = "gene_annotations", con = con)

result <- dbGetQuery(con, "SELECT * FROM gene_annotations")

df <-

Or just work with the DataFrame directly.

rdf <- session$sql("SELECT seqname, source, type, start, \"end\", score, strand, phase FROM gene_annotations")
arrow_table <- rdf$to_arrow()

df <- data.frame(arrow_table)
# seqname source type start end score strand phase
# 1 sq0 caat gene 8 13 NA + <NA>
# 2 sq0 caat gene 8 13 NA + <NA>
# 3 sq0 caat gene 8 13 NA + <NA>
# 4 sq0 caat gene 8 13 NA + <NA>
# 5 sq0 caat gene 8 13 NA + <NA>
# 6 sq0 caat gene 8 13 NA + <NA>

GitHub Sponsors​

We've added a GitHub Sponsors page. If you find our open source software useful, please consider sponsoring us.

Learn More: WHERE TRUE Technologies GitHub Sponsors

Wrapping Up​

In this post we covered two new features of Exon, table partitions and the ExonR SQL session. We hope you find these features useful and we look forward to hearing your feedback.

As always, if you have any questions or feedback, please reach out to us at

Β· 9 min read
Trent Hauck

This post highlights a couple of updates to the BioBear project to support SQL sessions and improvements to BAM file support in Exon so it can scale to larger full scans (like 14G of BAM files from a 10X Genomics experiment).

BioBear Update​

The main update to BioBear is that it now exposes Exon's inner query engine allowing for more streamlined application in ETL and ML use-cases. If you work in Biotech/Pharma, you probably watch your normie friends use tools like polars, DataFusion, and/or DuckDB to simplify their data processing with a mix of jealousy and contempt. They reap the benefits of faster/cheaper workflows, while you schlep GFFs and BAM files between CLI tools, workflows, and scripts.

With this BioBear release it becomes simpler to use Exon's query engine in your ETL jobs, ML pipelines, and other execution methods (like AWS Lambdas).

So what does that look like. First, install the latest BioBear version:

pip install -U biobear

Then, you can connect to a local Exon session:

import biobear as bb

session = bb.connect()

With that session, you can work with bioinformatic data along side CSV, Parquet, and JSON data. As an example, imagine the case where you wanted to combine and summarize the contents of a Metagenomics NGS sample that had been run through primary and secondary analysis.

For example here we have a sample, Ga0451106 from IMG/M. Let's say we want to store the gene annotations from the primary analysis in S3 as a Parquet file. We also want to be conservative with out storage duplication, especially sequences, so we'll join the protein FASTA on a PFAM GFF, so that we only duplicate the protein sequences that are annotated with PFAMs we care about given our end goal.

Write Gene Annotations to Parquet​

Taking the session from earlier, create an external table backed by the GFF file, then run a COPY query to write the results.

# Register the store we'll be writing to

# Create the external table, this could also be on S3
CREATE EXTERNAL TABLE gene_annotations
LOCATION 's3://wtt-01-dist-prd/TenflaDSM28944/IMG_Data/Ga0451106_prodigal.gff'

df = session.sql("""
COPY gene_annotations
TO 's3://wtt-01-dist-prd/gene_annotations/sample=Ga0455106/gene_annotations.parquet' (FORMAT parquet)

# shape: (1, 1)
# β”Œβ”€β”€β”€β”€β”€β”€β”€β”
# β”‚ count β”‚
# β”‚ --- β”‚
# β”‚ u64 β”‚
# β•žβ•β•β•β•β•β•β•β•‘
# β”‚ 7998 β”‚
# β””β”€β”€β”€β”€β”€β”€β”€β”˜

Say we did have the GFF in S3, we could load it into polars directly:

# Register the store we'll be reading from

# Create the external table, this could also be on S3
CREATE EXTERNAL TABLE gene_annotations_s3
STORED AS GFF LOCATION 's3://wtt-01-dist-prd/TenflaDSM28944/IMG_Data/Ga0451106_prodigal.gff'

df = session.sql("SELECT * FROM gene_annotations_s3").to_polars()
# shape: (5, 9)
# β”Œβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”
# β”‚ seqname ┆ source ┆ type ┆ start ┆ … ┆ score ┆ strand ┆ phase ┆ attributes β”‚
# β”‚ --- ┆ --- ┆ --- ┆ --- ┆ ┆ --- ┆ --- ┆ --- ┆ --- β”‚
# β”‚ str ┆ str ┆ str ┆ i64 ┆ ┆ f32 ┆ str ┆ str ┆ list[struct[2]] β”‚
# β•žβ•β•β•β•β•β•β•β•β•β•β•β•β•β•β•ͺ═════════════════β•ͺ══════β•ͺ═══════β•ͺ═══β•ͺ════════════β•ͺ════════β•ͺ═══════β•ͺ═══════════════════════════════════║
# β”‚ Ga0451106_01 ┆ Prodigal v2.6.3 ┆ CDS ┆ 2 ┆ … ┆ 54.5 ┆ - ┆ 0 ┆ [{"ID",["Ga0451106_01_2_238"]}, … β”‚
# β”‚ Ga0451106_01 ┆ Prodigal v2.6.3 ┆ CDS ┆ 228 ┆ … ┆ 114.0 ┆ - ┆ 0 ┆ [{"ID",["Ga0451106_01_228_941"]}… β”‚
# β”‚ Ga0451106_01 ┆ Prodigal v2.6.3 ┆ CDS ┆ 1097 ┆ … ┆ 224.399994 ┆ + ┆ 0 ┆ [{"ID",["Ga0451106_01_1097_2257"… β”‚
# β”‚ Ga0451106_01 ┆ Prodigal v2.6.3 ┆ CDS ┆ 2261 ┆ … ┆ 237.699997 ┆ + ┆ 0 ┆ [{"ID",["Ga0451106_01_2261_3787"… β”‚
# β”‚ Ga0451106_01 ┆ Prodigal v2.6.3 ┆ CDS ┆ 3784 ┆ … ┆ 114.400002 ┆ + ┆ 0 ┆ [{"ID",["Ga0451106_01_3784_4548"… β”‚
# β””β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”˜

Subsetting our Sequences​

As mentioned, it's important here to be cognizant of storage costs and thus reduce duplication into parquet except for amino acid sequences that likely contain a certain PFAM domain.

Similar to the GFF, we can create an external table for both the protein FASTA and the PFAM GFF:

# Create the external table, this could also be on S3
STORED AS FASTA LOCATION 'TenflaDSM28944/IMG_Data/Ga0451106_proteins.faa'

STORED AS GFF LOCATION 'TenflaDSM28944/IMG_Data/Ga0451106_pfam.gff'

# Register the store we'll be writing to

gff = session.sql("""SELECT * FROM pfam_gff""").to_polars()
# shape: (5, 9)
# β”Œβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”
# β”‚ seqname ┆ source ┆ type ┆ start ┆ … ┆ score ┆ strand ┆ phase ┆ attributes β”‚
# β”‚ --- ┆ --- ┆ --- ┆ --- ┆ ┆ --- ┆ --- ┆ --- ┆ --- β”‚
# β”‚ str ┆ str ┆ str ┆ i64 ┆ ┆ f32 ┆ str ┆ str ┆ list[struct[2]] β”‚
# β•žβ•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•ͺ═════════════════════════════β•ͺ═════════β•ͺ═══════β•ͺ═══β•ͺ════════════β•ͺ════════β•ͺ═══════β•ͺ═══════════════════════════════════║
# β”‚ Ga0451106_01_1000235_1003480 ┆ HMMER 3.1b2 (February 2015) ┆ PF14684 ┆ 673 ┆ … ┆ 100.900002 ┆ . ┆ null ┆ [{"ID",["Ga0451106_01_1000235_10… β”‚
# β”‚ Ga0451106_01_1000235_1003480 ┆ HMMER 3.1b2 (February 2015) ┆ PF14685 ┆ 753 ┆ … ┆ 81.900002 ┆ . ┆ null ┆ [{"ID",["Ga0451106_01_1000235_10… β”‚
# β”‚ Ga0451106_01_1000235_1003480 ┆ HMMER 3.1b2 (February 2015) ┆ PF03572 ┆ 875 ┆ … ┆ 70.400002 ┆ . ┆ null ┆ [{"ID",["Ga0451106_01_1000235_10… β”‚
# β”‚ Ga0451106_01_1000235_1003480 ┆ HMMER 3.1b2 (February 2015) ┆ PF07676 ┆ 459 ┆ … ┆ 16.799999 ┆ . ┆ null ┆ [{"ID",["Ga0451106_01_1000235_10… β”‚
# β”‚ Ga0451106_01_1000235_1003480 ┆ HMMER 3.1b2 (February 2015) ┆ PF07676 ┆ 408 ┆ … ┆ 15.3 ┆ . ┆ null ┆ [{"ID",["Ga0451106_01_1000235_10… β”‚
# β””β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”˜

# Join the protein FASTA and PFAM GFF and write the results to S3
df = session.sql("""
SELECT DISTINCT, fasta.description, fasta.sequence
FROM protein_fasta AS fasta
INNER JOIN pfam_gff AS pfam
ON = pfam.seqname
WHERE pfam.type = 'PF13561' -- Enoyl-(Acyl carrier protein) reductase
) TO 's3://wtt-01-dist-prd/sequences/pfam=PF13561/sample=Ga0455106/sequences.parquet' (FORMAT parquet)

# shape: (1, 1)
# β”Œβ”€β”€β”€β”€β”€β”€β”€β”
# β”‚ count β”‚
# β”‚ --- β”‚
# β”‚ u64 β”‚
# β•žβ•β•β•β•β•β•β•β•‘
# β”‚ 49 β”‚
# β””β”€β”€β”€β”€β”€β”€β”€β”˜

Exon BAM Update​

The other update to highlight here is that, Exon, and now by extension BioBear, has undergone optimizations that allow projection and predicate pushdowns to enable more efficient queries on BAM files.

Projection Pushdown​

For example, say we have we have a couple of BAM files from this 10X Genomics experiment. For simplicity lets assume one file for one sample from the treatment and one from the control, and we just want to look at the read name, the start position, and the map quality for QC purposes.

We can create an external table for the directory containing the BAM files - a listing table allows us to query the files in a directory as one table. Stop for a moment, and consider what the approach to working with multiple SAM files looks like with samtools. You'd have to write a script to loop over the files, then parse the output, and then combine the results. With Exon, you can just query the directory as a table.

$ ls -lh bam-files
-rw-r--r--@ 1 thauck staff 6.7G Sep 29 15:33 CytAssist_FFPE_Human_Colon_Post_Xenium_Rep1_possorted_genome_bam.bam
-rw-r--r-- 1 thauck staff 2.2M Sep 29 15:33 CytAssist_FFPE_Human_Colon_Post_Xenium_Rep1_possorted_genome_bam.bam.bai
-rw-r--r-- 1 thauck staff 7.0G Sep 29 15:55 CytAssist_FFPE_Human_Colon_Rep1_possorted_genome_bam.bam
-rw-r--r-- 1 thauck staff 2.3M Sep 29 15:55 CytAssist_FFPE_Human_Colon_Rep1_possorted_genome_bam.bam.bai

As you can see, this are a couple of larger files, totaling just under 14G for the main data files, and around 5M for the associated indexes.

import biobear as bb

session = bb.connect()


# See which columns are available
columns = session.sql("""
DESCRIBE ten_x_experiment
# print(columns)

df = session.sql("""
SELECT name, start, mapping_quality
FROM ten_x_experiment
# print(df.shape)
# (287822789, 3)

Reading about 285,000,000 records took around 3 minutes to load on my laptop, an M2 MacBook Air with 24GB of RAM. And while I recognize running on a local laptop isn't the most scientific, it does represent how many practitioners will work with data. In fact, I think that's an exciting thing about Exon and related tools: building off increased compute power for personal computers to enable local analysis of large datasets.

Predicate Pushdown​

We just pushed down the projection, i.e. which fields are "physically read", but we can also push down region filters, to determine which records are read in the first place, before hitting the query's predicate in the first place. This enables quickly subsetting files to just the region of interest.

import biobear as bb

session = bb.connect()

# Note that we've changed to an INDEXED_BAM table

df = session.sql("""
SELECT name, start, mapping_quality
FROM ten_x_experiment_index
WHERE bam_region_filter('chr1:1-1000000', reference, start, "end")
# print(df)
# shape: (39_090, 3)
# β”Œβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”
# β”‚ name ┆ start ┆ mapping_quality β”‚
# β”‚ --- ┆ --- ┆ --- β”‚
# β”‚ str ┆ i32 ┆ str β”‚
# β•žβ•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•ͺ════════β•ͺ═════════════════║
# β”‚ A00519:1665:H3LNHDSX7:3:2631:254… ┆ 69486 ┆ null β”‚
# β”‚ A00519:1665:H3LNHDSX7:3:2406:262… ┆ 69486 ┆ null β”‚
# β”‚ A00519:1665:H3LNHDSX7:3:2247:326… ┆ 69486 ┆ null β”‚
# β”‚ A00519:1665:H3LNHDSX7:3:2340:113… ┆ 69486 ┆ null β”‚
# β”‚ … ┆ … ┆ … β”‚
# β”‚ A00519:1665:H3LNHDSX7:3:2657:215… ┆ 999932 ┆ 0 β”‚
# β”‚ A00519:1665:H3LNHDSX7:3:2607:125… ┆ 999932 ┆ 0 β”‚
# β”‚ A00519:1665:H3LNHDSX7:3:2346:582… ┆ 999932 ┆ 0 β”‚
# β”‚ A00519:1665:H3LNHDSX7:3:2240:126… ┆ 999937 ┆ 0 β”‚
# β””β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”˜


This post highlight two recent updates to our tools:

  1. BioBear now exposes Exon's query engine allowing for more streamlined application in ETL and ML use-cases.
  2. Exon now supports projection and predicate pushdowns to enable more efficient queries on BAM files.

As always, feel free to reach out with questions, comments, or suggestions.

Β· 6 min read
Trent Hauck

While there's a slew of changes in the latest release of Exon, the most notable are the improvements in the VCF querying. This is the first release where we've been able to query VCF files with the same or better performance than BCFTools. This is a big deal, as BCFTools is the de facto standard for querying VCF files. Importantly, Exon is able to do this while maintaining the same SQL interface as the rest of the system. This means that you can use the same SQL query to query a VCF file as you would a CSV file.

With that, this post will touch on two topics related to the VCF querying improvements in Exon:

  • Query Rewriting
  • Performance Improvements

Query Rewriting​

Many bioinformatic file formats can be indexed and searched by genomic region. This presents an opportunity for query optimization, but also presents a challenge for the UI. How to expose this functionality to the user in a way that is germane to SQL and affords the user the ability to use the index to speed up their queries?

The direction we took was to use query rewriting to recognize SQL predicates that could be rewritten to a region expression, then during physical planning, reference the underlying index with the region to push the byte range down to the file read to speed up the query. As an example of this, consider the SQL predicate: WHERE chrom = 'chr1' AND pos BETWEEN 1000 AND 2000. This would get translated to a binary expression tree that looks like:

With this latest release, Exon will now traverse the tree and rewrite the predicate to a region. This is done through custom expressions and rules that govern the conjunction of those expressions. For example, after working through the original leaves of the tree, we would have a tree with custom expressions that look like:

Note that the chromosome field is sufficiently constrained to be a region expression by itself. And the less than and greater than expressions are rewritten to interval expressions.

This is then rewritten to combine the interval and region into a further constrained region expression:

And finally we can apply the rule again to get a single region expression:

This region is then used during physical planning to get the byte range. It's interesting to note, we also apply the filters after the byte range is read to guard against the challenges of the BGZF format returning a byte range that could contain records that don't match the region.

Performance Improvements​

With this release the VCF querying component of Exon got much faster and easier to use as the result of complementary changes. The end result is a querying engine that:

  • Uses query rewriting to recognize index regions from SQL queries. For example, WHERE chrom = β€˜chr1’ and pos BETWEEN 1 and 100 becomes the query range chr1:1-100.
  • Use TBI index files with the region to β€œpushdown” the region in the query to the specific byte ranges for the BGZF block offsets, then further seek to the uncompressed position within block location of the data.
  • Use the query projection to determine which parts of a VCF record to parse into a typed field. For example SELECT chrom, pos would cause only chrom and pos fields to generate a 'deserialization expense'.
  • Fan-out processing for each byte range for a given file. For example, if there were multiple chunks for a VCF file β€œA” and multiple chunks for a file B for a given region, these would be distributed among the available cores for parallel processing.

In visual form, this roughly looks like:

These changes were somewhat involved, but resulted in nice performance gains for the VCF subcomponent of Exon.

For example, working on the file ALL.chr17.integrated_phase1_v3.20101123.snps_indels_svs.genotypes.vcf.gz.tbi, a 3.7G file from the 1000 Genomes project, we can see the following performance when comparing Exon and BCFTools when querying the region 17:100-10000000.

Alt text

Here is another 1000 Genomes Project file, CCDG_14151_B01_GRM_WGS_2020-08-05_chr1.filtered.shapeit2-duohmm-phased.vcf.gz, a little less chonky at 2.6G, but still a good test case. Here we are querying the region chr1:10000-10000000.

Alt text

The exon-vcf-query-two-files row is two files queried in parallel. As you can see, there is little overhead when adding a second file, making Exon match the multi-file / multi-processor world of modern bioinformatics. To be transparent, Exon currently is a bit slower than BCFTools when querying a single file on an object store due to some inefficiencies in how remote indexes are read, but we believe we can close that gap in the next release.


With this release, Exon has reached performance equivalency with BCFTools on single-file reads, and has surpassed BCFTools on multi-file reads. We also believe this approach will allow us to continue to improve the performance of Exon across many indexable file types as we continue to work on the project.

Finally, thank you if you made it this far. We hope you enjoyed this post. If you have any questions or comments, please feel free to reach out to us on Twitter.

Β· 5 min read
Trent Hauck

We wanted to highlight three updates that we made in July 2023.

First, Exon now will rewrite queries to scan multiple files in parallel. This enables considerable speedups for queries over large datasets -- both for local files and object stores (e.g. S3, GCS, etc.).

Second, we're releasing an initial version of an MzML reader in our suite of tools. This is our first step towards supporting proteomics and metabolomics data in exon. This format is subject to change as we get feedback from users, so please let us know what you think!

Third, we're adding support for pandas dataframes in BioBear. This is a common request, so we're excited to be able to support it.

Parallel Scan​

Not only is going fast fun, but it's also important for enabling the fast iteration cycles necessary for innovation. To that end, Exon and related tools will now automatically parallelize scans over multiple files.

For example, if you have a directory with FASTA files, you can now do the following:

import biobear as bb
from pathlib import Path

data = Path("./data/") # folder with fasta files
df = FastaReader(data).to_polars() # need to install polars

And Exon will distribute reading the files across available cores. This is a huge win for data lakes, where you can now read multiple files in parallel without having to manually shard your data. E.g. here we see a 4x speed-up when reading 8 files.


MzML Reader​

MzML is a very common format in metabolomics and proteomics. At its core are measurements of the spectrum from the mass spec, but there's also a Controlled Vocabulary that describes various metadata about the experiment.

Similar to other readers, you instantiate a reader and then depending on what you want to do with it, you can convert it to arrow or polars with BioBear, or a data.frame with R.

import biobear as bb

# object stores and local files are supported
df = bb.MzMLReader("mzml-data/GNPS00002_A3_p.mzML").to_polars()

# shape: (5, 6)
# β”Œβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”
# β”‚ id ┆ mz ┆ intensity ┆ wavelength ┆ cv_params ┆ precursor_list β”‚
# β”‚ --- ┆ --- ┆ --- ┆ --- ┆ --- ┆ --- β”‚
# β”‚ str ┆ struct[1] ┆ struct[1] ┆ f32 ┆ object ┆ object β”‚
# β•žβ•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•β•ͺ═══════════════════════════════════β•ͺ═══════════════════════════════════β•ͺ════════════β•ͺ═══════════════════════════════════β•ͺ════════════════║
# β”‚ controllerType=0 controllerNumbe… ┆ {[80.948143, 80.993134, … 957.16… ┆ {[5416.88916, 7712.663574, … 480… ┆ null ┆ [('MS:1000579', {'accession': 'M… ┆ None β”‚
# β”‚ controllerType=0 controllerNumbe… ┆ {[80.284782, 81.017242, … 1176.3… ┆ {[4701.711426, 5527.709961, … 95… ┆ null ┆ [('MS:1000579', {'accession': 'M… ┆ None β”‚
# β”‚ controllerType=0 controllerNumbe… ┆ {[80.948288, 81.017365, … 1193.9… ┆ {[11152.501953, 9900.050781, … 8… ┆ null ┆ [('MS:1000579', {'accession': 'M… ┆ None β”‚
# β”‚ controllerType=0 controllerNumbe… ┆ {[80.948143, 81.017372, … 1074.1… ┆ {[6677.85791, 11401.181641, … 12… ┆ null ┆ [('MS:1000579', {'accession': 'M… ┆ None β”‚
# β”‚ controllerType=0 controllerNumbe… ┆ {[80.948174, 81.017387, … 968.84… ┆ {[6586.833984, 13542.833008, … 6… ┆ null ┆ [('MS:1000579', {'accession': 'M… ┆ None β”‚
# β””β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”˜

For R users, see the read_mzml_file function. And for exon-duckdb users see

Please see the docs for more information about MzML files, and again, please let us know if you have any feedback!

A Sneak Peak for Querying​

While it's not quite ready yet for BioBear and ExonR, in Exon, we've added a set of MzML specific functions for querying. For example, you can filter spectra based on the presence of a specific peaks.

For example, this will filter a set of spectra to only those that have a peak at 100.0 m/z that's within 0.1 m/z of the peak.

FROM mzml -- same table as above
WHERE contains_peak(, 100.0, 0.1) = true

This sort of declarative informatics is part of the Exon vision, which we'll be talking more about in the future.

A Note on Performance​

Similar to BioBear comparing favorably to other scientific data libraries, we see modest out-performance for MzML file reading.

The following compares reading using a few difference libraries in Python on an MzML file with about 8k spectra.


Pandas Support in BioBear​

There's not much to say besides that places where you could use to_polars you can now also use to_pandas. E.g.

import biobear as bb
from pathlib import Path

data = Path("./data/uniref50.fasta")
df = FastaReader(data).to_pandas() # need to install pandas

# id description sequence
# 0 UniRef50_A0A5A9P0L4 peptidylprolyl isomerase n=1 Tax=Triplophysa t... MEEITQIKKRLSQTVRLEGKEDLLSKKDSITNLKTEEHVSVKKMVI...
# 1 UniRef50_A0A410P257 Glycogen synthase n=2 Tax=Candidatus Velamenic... MKAIAWLIVLTFLPEQVAWAVDYNLRGALHGAVAPLVSAATVATDG...
# 2 UniRef50_A0A8J3NBY6 Gln_amidase domain-containing protein n=2 Tax=... MEILGRNLPRILGNLVKTIKTAPVRVVARRGARTLTQKEFGKYLGS...
# 3 UniRef50_Q8WZ42 Titin n=3053 Tax=cellular organisms TaxID=1315... MTTQAPTFTQPLQSVVVLEGSTATFEAHISGFPVPEVSWFRDGQVI...
# 4 UniRef50_A0A401TRQ8 Ig-like domain-containing protein (Fragment) n... PPSFIHKPDPQEVLPGSNVKFTSVVTGTAPLKVSWFKGTTELVAGR...


We hope you enjoy the new features and please let us know if you have any feedback! We'll be back next month with more updates.

Β· One min read
Trent Hauck

Conda has become a popular way to distribute software in the bioinformatics community. We're excited to announce that we've added BioBear to Conda Forge. You can now install BioBear with the following command:

conda install -c conda-forge biobear

Pip still works as well:

pip install biobear

Β· One min read
Trent Hauck

We're excited release ExonR. This is an R package that allows for interacting with Exon through an ergonomic R interface.


As a quick example, we can read in a GFF file from S3 and convert it to a GRanges object.


rdr <- read_gff_file(

df <-

gr <- GRanges(
seqnames = df$seqname,
ranges = IRanges(
start = df$start,
end = df$end,


If you're on an x64 machine, you should be able to install a pre-built binary from our R-universe.

install.packages('exonr', repos = c('', ''))

This should also build on other platforms, but you'll need to have Rust installed. The main Rust website has a guide for installing rust. Once you have rust installed, you can install ExonR from source with the command above.

Β· 7 min read
Trent Hauck

It's been around six weeks since our last public update. Here's what we've done:

  1. We've refactored our DuckDB extension into a standalone Rust library named Exon. This is a Rust-based library designed to implement a SQL engine that's aware of scientific data types and workflows.
  2. The DuckDB extension now utilizes Exon and has been renamed as Exon-DuckDB. This can be used with Python, R, and C++, wherever DuckDB is used.
  3. We've also released an open-source Python package, BioBear, which connects Exon with PyArrow and Polars.
  4. Exon, along with its DuckDB extension and BioBear, now supports Object Stores such as S3 and GCS. Local paths like ./path/to/file can be replaced with cloud storage paths like s3://bucket/path/to/file or gs://bucket/path/to/file, and the code will function the same.
  5. We've set up a documentation site with additional examples and tutorials, including Delta Lake integration and neighborhood analysis, similar to a map that helps users navigate.
  6. Finally, the libraries have been made open-source under permissive licenses. We hope that this will prompt others to use and contribute to the project, aiding in the development of a community around these tools.


Exon is a library written in Rust that takes advantage of DataFusion to develop a SQL engine proficient in handling scientific data types and workflows. It's designed for embedding into other applications and is the cornerstone of our DuckDB extension and BioBear packages.

This core infrastructure allows easy data management via Arrow and/or SQL and ensures adaptability across different execution environments. BioBear is specifically a Python package, but the Exon-DuckDB extension is adaptable, operating wherever DuckDB is used, such as Python, R, and JavaScript. We're currently exploring other language bindings, so feel free to reach out if you'd like to see a specific language supported.

See the Exon documentation, which has links to the installable crate, the Rust docs, and more.


For a brief demonstration, let's examine how we can use Exon to scan a GFF file, an output of CRT from a JGI dataset, and join the CRISPR array annotations with repeat units entirely within the array. If Rust isn't your focus and you're primarily interested in utilizing this code as a library, move forward to the BioBear section.

Fully Formed Example
use arrow::util::pretty::pretty_format_batches;
use datafusion::error::DataFusionError;
use datafusion::prelude::*;
use exon::context::ExonSessionExt;

async fn main() -> Result<(), DataFusionError> {
let ctx = SessionContext::new_exon();

let path = "./exon-examples/data/Ga0604745_crt.gff";
let sql = format!(


let df = ctx
r#"SELECT crispr.seqname, crispr.start, crispr.end, repeat.start, repeat.end
FROM (SELECT * FROM gff WHERE type = 'CRISPR') AS crispr
JOIN (SELECT * FROM gff WHERE type = 'repeat_unit') AS repeat
ON crispr.seqname = repeat.seqname
AND crispr.start <= repeat.start
AND crispr.end >= repeat.end

ORDER BY crispr.seqname, crispr.start, crispr.end, repeat.start, repeat.end
LIMIT 10"#,

// Show the logical plan.
let logical_plan = df.logical_plan();
format!("\n{:?}", logical_plan),
Limit: skip=0, fetch=10
Sort: crispr.seqname ASC NULLS LAST, crispr.start ASC NULLS LAST, crispr.end ASC NULLS LAST, repeat.start ASC NULLS LAST, repeat.end ASC NULLS LAST
Projection: crispr.seqname, crispr.start, crispr.end, repeat.start, repeat.end
Inner Join: Filter: crispr.seqname = repeat.seqname AND crispr.start <= repeat.start AND crispr.end >= repeat.end
SubqueryAlias: crispr
Projection: gff.seqname, gff.source, gff.type, gff.start, gff.end, gff.score, gff.strand, gff.phase, gff.attributes
Filter: gff.type = Utf8("CRISPR")
TableScan: gff
SubqueryAlias: repeat
Projection: gff.seqname, gff.source, gff.type, gff.start, gff.end, gff.score, gff.strand, gff.phase, gff.attributes
Filter: gff.type = Utf8("repeat_unit")
TableScan: gff"#,

// Uncomment to show the physical plan, though it's obviously messier.
// let physical_plan = df.create_physical_plan().await?;
// println!("Physical plan: {:?}", physical_plan);

// Collect the results as a vector of Arrow RecordBatches.
let results = df.collect().await?;
let formatted_results = pretty_format_batches(results.as_slice())?;
format!("\n{}", formatted_results),
| seqname | start | end | start | end |
| Ga0604745_000026 | 1 | 3473 | 1 | 37 |
| Ga0604745_000026 | 1 | 3473 | 73 | 109 |
| Ga0604745_000026 | 1 | 3473 | 147 | 183 |
| Ga0604745_000026 | 1 | 3473 | 219 | 255 |
| Ga0604745_000026 | 1 | 3473 | 291 | 327 |
| Ga0604745_000026 | 1 | 3473 | 365 | 401 |
| Ga0604745_000026 | 1 | 3473 | 437 | 473 |
| Ga0604745_000026 | 1 | 3473 | 510 | 546 |
| Ga0604745_000026 | 1 | 3473 | 582 | 618 |
| Ga0604745_000026 | 1 | 3473 | 654 | 690 |



BioBear is a Python package that extends Exon, providing it with a Pythonic interface. For instance, you can read a GFF file from S3, and then load it into a PyArrow RecordBatch Reader and/or a Polars DataFrame.

PyArrow's strength lies in its ability to render our domain-specific data highly portable. For instance, suppose you have a Python job that produces a GFF file, perhaps the output of Prodigal. You can create an Arrow RecordBatch Reader that streams data from S3 into a Delta Lake table.

import biobear as bb
from deltalake import write_deltalake

batch_reader = bb.GFFReader("./job/output/test.gff").to_arrow()

write_deltalake("s3a://bucket/delta/gff", batch_reader, storage_options={"AWS_S3_ALLOW_UNSAFE_RENAME": 'true'})
# aws s3 ls s3://bucket/delta/gff
# PRE _delta_log/
# 2023-06-24 11:00:19 8509556 0-ccedd844-373f-4e70-a99e-2167535fcf35-0.parquet

You can also use BioBear to query local indexed files. For example, you can query a BCF file for records on chromosome 1.

import biobear as bb

reader = bb.BCFIndexedReader("example.bcf")
df = reader.query("1")

In this case, the query is executed by the BCFIndexedReader, which uses the index to only read the records on chromosome 1. This is much faster than reading the entire file and filtering in memory.

Object Stores​

Scientific computing is increasingly done in the cloud -- the data that gets generated from workflows is plopped somewhere in you favorite object store (e.g. S3). This has made it less expensive to store the output but adds an additional layer of complexity when trying to do analysis.

To try to mitigate this complexity WHERE TRUE's tools now support reading from object stores. For example, we could rewrite the last example to read from S3:

import biobear as bb
from deltalake import write_deltalake

batch_reader = bb.GFFReader("s3://bucket/job/output/test.gff").to_arrow()
write_deltalake("s3a://bucket/delta/gff", batch_reader, storage_options={"AWS_S3_ALLOW_UNSAFE_RENAME": 'true'})

Put this in a lambda and you're about 3/4ths of the way to a cloud-based bioinformatics data platform.

Or, if DuckDB is more your speed, you can do:

FROM read_gff('s3://bucket/job/output/test.gff')

Better Home and Docs Site​

We'll, you're here aren't you... kidding of course, but we've deployed an update to the main site and the docs site. The docs have more examples. We gave the example earlier of how to use BioBear to write a Delta Lake table from a GFF file. We also have an example of how to use Exon-DuckDB to do neighborhood analysis on a metagenomics sample.

Have a gander at our main site here.

Open Source​

The ultimate goal of WHERE TRUE Technologies is to not exist. We want to build tools and popularize techniques that diminish the need for the majority of specialized bioinformatics file formats in favor of more general-purpose formats that are easier to work with, but don't make tradeoffs on performance or flexibility.

To get to that state, we've opened sourced our libraries under permissive licenses. We hope that this will encourage others to adopt and contribute to the project, and help us build a community around these tools.

You can review the licenses for each of the libraries at the following links: